78465 Insel Mainau, Germany
They have beautiful gardens with different themes.The kids loved the big peacock and duck formed flowers.We visited at the beggining of spring which was still a bit cold but sunny,perfect weather to walk around.They also have playgrounds and picnic place all over the place whenever you want to have a break after a long walk.
When i first saw the place ,it reminds me of the "secret garden" cartoon series that i used to watch when i was a kid.
They also offer different activities for the kids like treasure hunt,children's tour,pony rides etc.
It's worth a visit specially in spring when the flower bloom everywhere.
Here's the website for the full information: