Just outside of Kalkar in NRW lies a huge nuclear reactor that was ultimately never taken online. The SNR-300 "Fast Breeder" (a neutron reactor that creates more fuel than it uses) was needed since Germany has a limited supply of uranium and wanted to limit imports.

When dutch businessman Hennie van der Most bought the complex in 1995, he decided to turn it into a hotel and amusement park - "Kernwasser Wunderland", later renamed to "Wunderland Kalkar".

Via Google Sightseeing: Nuclear Water Wonderland.