Mainau - the flower island - had many owners before it was bought in 1853 by Grand Duke Friedrich I of Baden as a personal property. He is considered being the park founder. He not only built a summer residence, 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.

In the 1930, Prince Wilhelm (then the island's owner) turned the administration of Mainau over to his son, the Swedish Prince Lennart Bernadotte II. The prince, who had renounced his Swedish royal lineage after marrying a commoner, devoted the rest of his life to turning the island into a privately-operated park. Mainau is now maintained by a foundation that the prince and his second wife established. The island's manager is their daughter, Countess Bettina Bernadotte and their son, Count Björn Bernadotte, manages the foundation.
The Bernadotte family still lives in the castle on the island.

Mainau - with 45 hectare the third largest island in Lake Constance - has a kind of micro Mediterranean climate. Nowadays it offers the beauty of impressive and colourful themed gardens ( for instance a Rhododendron slope, Italian Rose garden and Dahlia garden - www.ipernity.com/doc/294067/48516738 ) and a very interesting park-like arboretum with 500 different species. A greenhouse has a tropical climate and houses thousands of butterflies.

The flower island is the main attraction of Lake Constance and attracts a lot more than a million visitors each year. Although not the main reason for visiting, parts of the 18th century castle (large PiP ) are open to the public.