The Mainau Island is a small island (45 ha) in the north-western part of Lake Constance, the Überlinger See. It can be reached from the south bank via a bridge and has its own jetty. The next larger cities are Konstanz, Meersburg and Überlingen.
The island belongs to the Litzelstetten-Mainau district of the city of Konstanz and is owned by the Swedish-born aristocratic family Bernadotte. Due to the favorable climate at Lake Constance, palm trees and other Mediterranean plants grow in the castle park. That is why Mainau is also called the flower island in Lake Constance. It is accessible to tourism and a well-known excursion destination. On the Mainau there is also a small pet zoo (sheep, goats, etc.), a butterfly house with tropical butterflies, mainly of South American origin, flying around freely between the visitors, a peacock enclosure and some dining facilities. The Mainau is located on the Upper Swabian Baroque Road.
The first traces of settlement date from the Neolithic around 3000 BC. In the year 15 BC The Romans subjugated the local Celts and used the island for a fort, a shipyard and a naval station for the Roman Bodensee war fleet.
Reichenau Monastery owned the island from the 9th to the 13th century. Then she went to the Teutonic Knights. Under their order builder Johann Caspar Bagnato, the construction of the baroque church of St. Mary and the baroque castle began in 1732. The frescoes in the church were created by Franz Joseph Spiegler in 1737/1738. Due to the secularization under Napoléon Bonaparte in 1806, the Teutonic Order also lost the Mainau; various private owners took turns until the island was acquired as a summer residence by the Baden Grand Duke Friedrich I in 1853.
He had the island redesigned by his court gardeners Chr. Schlichter and above all Ludwig Eberling, who from 1856 was in the service of the Grand Duke for 42 years. Mediterranean and exotic plants were procured, avenues, gardens, an arboretum and a new system of paths were created. The island owes its present appearance to Friedrich's visions and ideas and the skill of his court gardener. Even if Mainau was left to decay after Friedrich's death in 1907, the foundation stone for the much-vaunted flower island was laid during his reign.
By inheritance, the island came into the possession of the Swedish royal family in 1928. Gustaf Lennart Nikolaus Paul Bernadotte retired to the Mainau after leaving the royal family of Sweden in 1932 and expanded it into today's publicly accessible flower island. He died on December 21, 2004 at the age of 95 in the island's castle.
In 1974 the entire Mainau was brought into the Lennart Bernadotte Foundation. Insel Mainau is managed by Insel Mainau GmbH, whose share capital is 99% owned by the foundation and 1% owned by the Bernadotte family. Insel Mainau GmbH is a private company without public subsidies. Countess Sonja Bernadotte was managing director of Mainau GmbH from 1981 to 2006, and in 2007 her eldest daughter, Countess Bettina Bernadotte, took over this position.
In 2005, 1,2 million tourists came to the island of Mainau. In 2007 the artist Stefan Szczesny wants to convert the island into a total work of art.