Pre-history and early history

Remains of pile dwelling settlements found on the banks of Lake Constance, allow us to assume that the island of Mainau was inhabited even early on. A settlement consisting of six houses was excavated on the South bank of the island, and dated to the Neolithic period. Around 400 BC, the island was allegedly part of the Celtic settlement. However, corresponding settlement remains were never found. 

From 15 BC, the Lake Constance region belonged to the Roman province of Rhaetia. Although not proved by remains, it is assumed that Mainau was used as a naval base in this context. Around 400, the Roman rule of Lake Constance ended. The Romans followed the Alemanni. In the 5th and 6th centuries, the island of Mainau was an Alemannic duchy, then later part of a Franconian kingdom managed from Bodman.

In 724, the travelling bishop Pirmin founded a Benedictine monastery on the biggest island on Lake Constance, the island of Reichenau, which developed into a spiritual centre of the Western world in the following centuries. Even shortly after founding, the monastery of Reichenau was given further settlements on the mainland opposite the island. Allegedly, the island of Mainau was given to the monastery of Reichenau in this way, in 724. As administrators, ministers settled on Mainau, who also built a castle on the island, first mentioned in 1272. Even today, noticeable traces to the south of the castle point to an extensive fortification. From the 13th century, the monastery of Reichenau continued to decrease in importance, which ultimately also led to the minister Arnold von Langenstein giving Mainau including all lands on the mainland, to the Teutonic Order in 1271. In turn, the Order accepted two of his sons.

The Teutonic Order on Mainau

The era of the Teutonic Order is a significant milestone in the long history of the island of Mainau. A time, whose traces are still clearly visible today, above all with the prominent Baroque building complex of castle and church. The commanders of the ecclesiastical order of knights, founded at the time of the crusades, prevailed as the administrators of the settlement of this order on the island, until 1806, so over 500 years. However, after bestowal, Mainau including all the accompanying lands on the mainland, initially went to the settlement of the Teutonic Order in Castle Sandegg near Salenstein, in the neighbouring canton of Thurgau. In 1272, the commandry of Sandegg was dissolved and relocated to Mainau. There, the castle was expanded, the acquisition of goods by the Teutonic order was extended to the north, so that the commandry of Mainau ultimately developed into the most wealthy settlement of the province of the order Alsace-Burgundy. 

During the Thirty Years War (1618–48), Sweden also took over the rule of Mainau for two years. If the island was initially a safe place of refuge, the Swedish troops still succeeded in taking it over in 1647. Only in the end phase of the war was Mainau secured by a closed earthwork system, from which only a few remains are recognisable today.

After the Westphalian Peace in 1649, the Swedes moved out, but not without having raided and plundered the island. Only the so called “Swedish cross” was apparently too heavy for them, which is why, according to legend, the crucifixion group cast in bronze in Constance in 1577, was left in the shallow water between the island and the mainland. Later, it was erected there, and today greets visitors to Mainau as the “Swedish cross”.

The order commandry of Mainau took a long time to recover from the consequences of war. Yet, it could be seen as the start of a new era, that the Provincial Superior of the order province of Alsace-Burgundy issued the authorisation to build a new church on the island. The contract was awarded to the architect of the order Johann Caspar Bagnato (1696-1757), who started to build the Baroque church in 1732. In 1739, the castle church of the virgin Mary was inaugurated, and in the same year, Bagnato also received the contract to build a castle on the island. The castle previously used as the seat of the commander, was demolished for the new building. After a seven-year building period, the castle of the Teutonic Order was closed in 1746. The magnificent coats of arms on the gables of the middle wing, are still reminiscent of the builder, even today. 

In the course of secularisation, the Teutonic Order Commandry of Mainau was dissolved in 1806, and became part of the newly founded Grand Duchy of Baden, with all possessions.

19th century

With the end of the Teutonic Order of knights on Mainau, a period of almost 50 years of uncertainty and decline started for the island, with many changes in ownership. The reigning Grand Duke Karl Frederick had little interest in the small island on Lake Constance, during the Napoleonic War. From 1811 to 1818, his grandson Karl Ludwig Frederick succeeded him, who had just as little enthusiasm for Mainau.

His successor Grand Duke Ludwig von Baden finally sold the island to the Hungarian Prince Nikolaus of Esterházy in 1827 for 65,000 guilders, who planted the first exotic plants on the island, including a fig trellis on the front of the castle, which is still there today. Three years later, Prince Esterházy bequeathed Mainau to his son out of wedlock Nikolaus, which the Grand Duke previously elevated to Baron of Mainau. Without having showed a great deal of dedication to the island, he sold Mainau to Countess Katharina von Langenstein after 9 years,

which is why the island, which they gave to the Teutonic Order in 1271, became the property of the von Langenstein family again after more than 500 years. In turn, 9 years later, Countess von Langenstein sold the island to her daughter Louis, who married the Swedish Count Douglas. The couple wanted to sell the island again soon after that, and finally found a buyer in Grand Duke Frederick I of Baden, Great Grandfather of Lennart Bernadotte, in 1853.

Today, the Baden Grand Duke is seen as the park founder. He not only set up his summer residence here, but began to create order on the island to redesign it and plant rare exotic trees and plants, which he brought back from his travels. Significant parts of the Mainau park, such as the arboretum, Italian rose garden and orangery go back to this time, as well as the first winter protective houses for exotic plants, and the first iron bridge as a connection to the main land.

The history of the island in the 20th century

After the death of Grand Duke Frederick I in 1907, Mainau went to his son, Grand Duke Frederick II. He bequeathed the island to his sister Viktoria, Queen of Sweden, which is how the island of Mainau became the property of the Swedish royal family in 1928. After the death of Queen Viktoria, the island went to her son Prince Wilhelm of Sweden in 1930, who transferred the management of the inheritance to his son Lennart in 1932, who was just 23 at the time. In the same year, Lennart Bernadotte moved back from Sweden to Main, after he lost all titles and claims to inheritance to the Swedish royal family, after marrying the commoner Karin Nissvandt, and made the island into a new residence for him and his family. Lennart Bernadotte began to convert the neglected island into a park again, little by little and with a great deal of effort, soon opened Mainau to visitors, and the “Schwedenschenke” restaurant was opened to cater for them. In the years before the Second World War, Mainau profited not insignificantly from state managed tourism, the “Kraft durch Freude” (Strength through Joy) travels, which brought thousands of visitors to the island.

War and post war period

Even before the start of the war in 1939, Lennart Bernadotte left the island He spent the time until the end of the Second World War with his family in Sweden. A married couple were appointed as administrators, to manage the building, park, garden and also the visitors to Mainau, and were able to take care of the facilities and the business, until the administrator was called up to the German Army in 1942. In this situation, a request from the Todt Organisation was convenient for Prince Wilhelm of Sweden and his son Lennart Bernadotte. The structural engineering organisation of the Ministry of Defence wanted to rent Mainau for the duration of the war, and set up a rest home for officers and industrialists. The rental contract came to pass, and from mid 1943, Mainau was managed by the Todt Organisation. The rest home was to be set up in the castle and archway building, and three additional wooden barracks were built to accommodate the staff. A water pipeline was also laid from the Constance district of Egg to the island. So, everything was prepared, yet high ranking employees of the Todt Organisation no longer had the opportunity to recover on Mainau.

Instead, shortly before the end of the war, the Foreign Office gave the island to French collaborators, who rallied around the head of the extreme right wing “Parti Populaire Français” (PPF), Jacques Doriot. From the south of Germany, the group planned to drive the Gaullists and communists out of France, which is why Doriot proclaimed a French liberation committee on the island of Mainau at the beginning of 1945. However, this German – French collaboration ended in February 1945, with the death of Doriot, in a low flying aeroplane bomb attack near to Mengen. As a result, his followers fled Mainau.

On 26 April 1945, a new era began for Constance and the surrounding area: The region became part of the French occupation zone. Mid May 1945, the islands of Mainau and Reichenau were cleared. The islands were selected for the accommodation and recovery of French prisoners liberated from the Dachau concentration camp. A total of several thousand prisoners were brought to Lake Constance, most of which to Reichenau. The castle on Mainau and the barracks built by the Todt Organisation now stood empty. They now served as accommodation, above all for seriously ill and particularly weakened former concentration camp prisoners, who were treated, cared for and supervised by French doctors, and French and German nurses, according to the latest perspectives. Yet for 33 of them, it was too late to help them. In spite of good care, they died during their stay on Mainau, and were initially buried in a temporary grave yard on the east bank of the island. After his first visit to the island after the end of the war, Lennart Bernadotte arranged for the dead to be buried in the Constance main cemetery. Between 1947 and 1949, the human remains were then sent to France.

In September 1945, the military hospital on Mainau was dissolved and the former concentration camp prisoners who had regained their strength were taken to France. The French occupying troops also ultimately left Mainau again. When Lennart Bernadotte came back to the island for the first time in January 1946, by his own account, he found a deteriorated facility and a mostly empty castle. A long conflict arose with the French authorities regarding the regulation of the damages, and the replacement of missing furnishings. The construction and repair works in the part and garden were difficult, however Mainau was soon open to visitors again.

In order to open a “window to the world” for young people after the destruction of the war, even in 1946, Lennart Bernadotte offered meetings and leisure time for young people on Mainau, in the framework of the Young Men's Christian Association (YMCA) – today the Christian Young People's Association – under Swedish management. The participants were initially housed in the barracks built by the Todt Organisation, which were torn down in 1951. In these difficult post war years, the care sometimes came from Sweden and Switzerland. The aim was to allow young people war-damaged young people to recover, and have international meetings with young people from other countries.

This institution developed into the “International Institute Castle Mainau”, which began operation in 1949, under the sponsorship of the YMCA world association, in a wing of the castle, and offered courses, seminars and workshops on youth issues in various areas. By the time the institute closed at the end of 1968, around 20,000 participants from 40 countries had attended the events at Mainau Palace.

The Bernadotte Family

Count Lennart Bernadotte

Mainau was his life's work, “gardening for the good of the people” was his motto. On 8 May 1909, Count Lennart Bernadotte was born as Prince Gustaf Lennart Nikolaus Paul, son of Prince Wilhelm of Sweden, and the Russian Grand Duchess Maria Pawlowna in Stockholm. In 1932, the qualified farmer and forest took on the management of the island of Mainau, which belonged to his father at the time. He moved back to Lake Constance together with his family, after he lost all titles and claims as a member of the royal family, after marrying the commoner Karin Nissvandt. Only in 1951, a distant relation, Grand Duchess Charlotte von Luxemburg, awarded him and his two cousins who also married commoners, the title “Graf af Wisborg” (Count of Wisborg).

During the Second World War, the family stayed in Sweden, were Lennart Bernadotte was known as a photographer and film producer. He was the Editor in Chief of the magazine “Foto”, and founded “Artfilm” together with partners, whose greatest success was the documentary film about the Pacific crossing by the Norwegian naturalist Thor Heyerdahl with his raft Kon-Tiki. The documentary film was awarded an Oscar in 1951.

After the Second World War, Lennart Bernadotte finally moved back to the island on Lake Constance with his family. He opened the park and garden to the public, and made Mainau the most important tourist destination on Lake Constance, with around 1.2 million visitors every year. The Mainau boss was dedicated to conservation even at an early age. He founded the German Council for Landscape Management, and was the president of the German Horticultural Society. The “Green Charter of Mainau” that he initiated in 1962, is still valid today. Together with the Lindau doctors Gustav Parade and Franz Karl Hein, he initiated the Noble prize winner conferences in Lindau, and very quickly became the driving force behind the annual meeting. As the first president of the board of trustees for the conferences of Nobel prize winners in Lindau, he structured the development of the Lindau dialogue from 1951, right from the start.

After his withdrawal from the Mainau company, Lennart Bernadotte increasingly dedicated himself to his hobby, macrophotography. His “visual dreams” were very well received at numerous exhibitions all over the world. Count Lennart Bernadotte died on 21 December 2004 at the age of 95.

Countess Sonja Bernadotte

Initially a playground, then training and work place and finally a purpose in life: For Countess Sonja Bernadotte, born in 1944 in today’s Constance district of Litzelstetten, Mainau was home. As her parents worked on the island, she more or less grew up there. In 1969, she became assistant to the head of the island, who she married in 1972. Together with Count Lennart Bernadotte, she made the island of Mainau what it is today: the biggest and most important tourism company on Lake Constance.

In 1981, Lennart Bernadotte handed over the management of Mainau GmbH to his wife. For 25 years, Sonja Bernadotte controlled the fate of the company, primarily led by her love of nature. The programme was continually further developed and adapted to the changing needs of the visitors. Yet, even beyond Mainau, Countess Bernadotte took on the tasks of her husband. So, amongst other things, she was the President of the German Horticultural Society, and President of the board of trustees for the conferences of the Nobel prize winners in Lindau.

At the age of 62, she withdrew from operative business and handed over the management of Mainau GmbH to Countess Bettina Bernadotte, the eldest of her five children. After a short illness, the former Mainau boss died in 2008, at the age of 64.

Countess Bettina Bernadotte

Countess Bettina Bernadotte is the oldest of the five children of Sonja and Lennart Bernadotte. Today, she controls the destiny of the tourism company, as the Managing Director of Mainau GmbH, together with her brother Björn. Born in 1974, after several language stays, she studied tourism business management at the University of Co-operative Education in Ravensburg, Baden-Württemberg. In 2002, the qualified business economist took on her role in the Mainau company, and work as a personal assistant to her mother from 2002 to 2006. Since January 2007, Bettina Bernadotte has been the Managing Director. She is also President of the board of trustees, for the conferences of Nobel prize winners in Lindau, member of the board of directors of the Deutsche Gartenbau-Gesellschaft (German horticultural society), member of the board of trustees of the child welfare organisation Plan International, and a member of the administrative board of the University of Hohenheim, patroness of Europa Miniköche (EU Mini-Chefs) and Managing Director of Minigärtner gGmbH (Mini-Gardeners).

Count Björn Bernadotte

The eldest son of Sonja and Lennart Bernadotte, born in 1975, has been the Managing Director of Mainau GmbH since 2011. Before that, he completed a degree in social education in Rorschach (Switzerland), alongside a commercial education. He not only uses the knowledge that he gained from this, in his work as Managing Director at Mainau GmbH. He also uses it in the course of his work for the charitable Lennart Bernadotte Foundation. Count Björn Bernadotte lives together with his wife Sandra in the Baroque palace on the Flower Island of Mainau.

Historical Buildings

Palace Church St. Marien

The first section of the Baroque new building, which the Teutonic Order built on the high plateau on the island, was the Castle Church St. Marien. On the foundations of a previous building from the 13th century, the Baroque building was built between 1732-39, according to plans of the architect of the order Johann Caspar Bagnato. He created a four-axle hall, with transept like extensions for the galleries, including a connecting passage to the castle, and a round, closed choir. Bagnato commissioned well known artists with the interior design: altars, pulpit and busts came from Joseph Anton Feuchtmeyer, who was one of the most important sculptors in the Lake Constance region at the time. The stuccos were created by Francesco Pozzi and his sons, frescos, ceilings and altar paintings are the work of Franz Joseph Spiegler.

Palace Mainau

Immediately after completion of the church, Bagnato started with the rebuilding of the neighbouring castle, conceived as a residence of the commander of the order, and built between 1739 and 1746, in the place of the Medieval castle complex. The three storey Teutonic Order palace, surrounded by a commemorative courtyard, turned its wings towards the island, while the main side faces the lake. What is noticeable in the middle risalit of the main wing, is the coat of arms of the Teutonic Order, which can be seen from afar. The interior design is rather reserved, with modest staircases, in complete contrast to other Baroque Palaces on Lake Constance. The state rooms in the middle wing, show stucco ceilings from the Pozzi workshop, and intarsia doors and Steckborn tiled stoves. The centre is the two-storey former audience hall, the “White Hall” which gained its current appearance in 1875.

Comturey tower

The oldest still existing “stone witness” of the long history of the island, is today's Comturey tower. The massive building was originally part of the Medieval fortifications, built at the time of the Teutonic Order. It was allegedly built as a residential tower between 1200 and 1240. In connection with the construction of the Baroque palace in the 18th century, the upper floors of the tower were removed, and replaced with a terrace. A cellar vault, driven deep into the rock, served as a food store and press house.

Since spring 2014, the visitors have opened up new prospects from the Comturey tower. In the course of the redesign of the harbour area, the former defence tower was integrated into the roof garden of the Comturey restaurant, and forms the centre piece of this part of the park. Inside the restaurant, glazed atriums give a clear view of the front of the tower.

Swedes’ Tower

Also part of the late Medieval fortifications, is the vineyard tower on the South West side of the island, called the “Swede's tower” in memory of the time of the Swedish occupation of Mainau. The date 1558 over the entrance door, and the coat of arms of the Teutonic Order point to its date of origin, apparently originally built as a watch tower in the direction of the main land. Its current shape with helm roof and wooden boarding comes from the 19th century.

Gardener's tower

On the remains of the Medieval fortress so to speak, the gardener's tower stands on the edge of the castle square. Remains of the fortress walls can still be seen in the surrounding area. The massive lower floors of the tower are still part of the original building structure, while the octagonal structure and the helm roof came from the 19th century.

Archway Building

The archway building still marks the entrance to the castle area, even today. It is assumed that the gate to the castle complex was located here in Medieval times, especially as the castle moat ran here. The Baroque gatehouse arose from this in the time of the Teutonic Order, probably built by Franz Anton Bagnato, the son of the great Baroque architect. In any case, the year 1764 and the coat of arms of the provincial commander point to this. The classical annex comes from the 19th century. Today, parts of the administration of Mainau GmbH are housed in the gateway building.

History of the garden

On old plans, it can be seen that the island of Mainau was already used for horticultural uses early on. At the latest, at the time of the Teutonic Order, ornamental and kitchen gardens were created on the island in the area of the castle complex, while the shore area was used for agricultural uses. Even the oldest still existing tree stock, the linden trees on the East side of the island, go back to this time. A first garden area was created at the beginning of the 19th century, under Prince Esterhazy, who planted the first exotic trees and rare plants on the island. However, Grand Duke Frederick I of Baden was crucial to the further development of Mainau as a flower and plant paradise. He developed an overall concept to open up the island with paths, alleys and viewing spots, and gradually implemented it, from 1853 until his death in 1907, together with his court gardeners. In doing so, he created the basis for the current design of Mainau. The park inside the island, the arboretum with tree stock that is now 100 to 150 years old, was created at the time of Frederick I, who brought numerous exotic trees with him from his travels. The Italian rose garden on the South side of the castle also goes back to the time of the Grand Duke. He had a flower garden created in the Italian style in 1860.

Even at the time of the Teutonic Order, wine was grown on Mainau, even though the vineyard laid out on the south west slope of the island, near the “Swedish tower”, comes from Frederick I. At the time, vineyard walls were built, the soil was replaced, and grape varieties were experimented with. Even today, an excellent Lake Constance wine flourishes here. The wine education path provides information about the history and development of wine growing on Lake Constance, and especially on Mainau.

After the death of Frederick I, at the request of his widow, nothing about the park and garden was allowed to be changed. Therefore, in 1932, Lennart Bernadotte took over a park overgrown with local vegetation, in which initially more had to be dug up than planted. Based on the foundations established by Frederick I, Lennart Bernadotte gradually developed today's “Flower Island of Mainau”, his life's work.

Initially, the previous arboretum was cleared of wild growth, and lines of sight were exposed – it was no easy decision to decide which tree should be felled, but ultimately, on an island, one should always have a view of the water. He initially photographed a section of the park, retouched it for better assessment on the photo, of which trees should go, and only then felled them. Initially the basic structures of the original park were restored, and then the further design was started. From 1950, the development of the Flower Island continued full steam ahead. In 1955, there was already a “real” Mainau flower year, with orchid show, spring changing flora, rhododendrons, roses, summer changing flora, citrus collection, fuchsia collection and dahlias. Gradually, the historical buildings were also renovated inside and out, with the castle and castle church. In 1968, a large palm house was built to replace the former winter greenhouses. Not least, the necessary island infrastructure had to be created: a pumping station for Lake Constance water, to irrigate the park facilities, drainage through the lake floor, telephone lines and roads. The park and tourist infrastructure were developed according to supply and demand. There was no general plan, which distinguished the island of Mainau from many other parks.

Today, the park and garden of Mainau attract approx. 1.2 million visitors per year. 25 hectares of the total 45-hectare island are showcase areas today. And the park is continually being further developed. In 2003, the island of Mainau was placed under a preservation order, as a complete ensemble, and part of the island was entered into the book of monuments as a “cultural monument of particular importance”. The castle, castle church, harbour, the Italian rose garden, parts of the arboretum and all historical fortification walls are under the highest protection level. With the focus on monument protection, and also protective categories of conservation, the sensitive further development of the island is being continued by the Bernadotte family in cooperation with the relevant authorities.


  • Blumeninsel Mainau GmbH: „Kreuz und Schwert“, Ausstellungskatalog 1991
  • Blumeninsel Mainau GmbH: „Lennart Bernadotte“, Ausstellungskatalog 1992
  • Burchardt, Lothar; Engelsing, Tobias; Klöckler, Jürgen: „Gutachten – Lennart Bernadotte (1909-2004) während der Zeit des Nationalsozialismus und in den unmittelbaren Nachkriegsjahren“. 2014; Download hier
  • Dées de Sterio, Alexander und Johanna: „Die Mainau – Chronik eines Paradieses“. Belser Verlag Stuttgart, 1977
  • Graf Bernadotte, Lennart: „Ein Mann Eine Insel Ein Lebenswerk“. Blumeninsel Mainau GmbH, 1992
  • Graf Bernadotte, Lennart: „...ein Leben für die Mainau“. Stadler Verlag, 1996
  • Graf Bernadotte, Lennart: „Gute Nacht kleiner Prinz“. Heyne Verlag München, 1987
  • John, Timo: „Eine Familie aus Schweden auf der Bodenseeinsel Mainau“. Kunstverlag Josef Fink, 2009
  • Burchardt, Lothar: „Stadtgeschichte Konstanz“, Band 4
  • Moser, Arnulf: „Die andere Mainau“, Universitätsverlag Konstanz, 1995
  • Orlik, Roger: »…Der König vom Bodensee«, Albstadt: SP Verlag 2002
  • Pfindel, Judith; Meier, Heinz-Dieter: „Die Pflanzenwelt der Mainau“. Hampp Verlag, 2005
  • Wendt, Gunna: „Die Bernadottes und die Romanoffs“. Huber Verlag Frauenfeld, 2009
  • Wendt, Gunna: „Gräfin Sonja Bernadotte“. Droste Verlag Düsseldorf, 2010


© 2023 | Mainau GmbH - All rights reserved | Imprint | Privacy Policy