The Radisson Blu Hotel, Berlin (Germany), which is situated on the River Spree, directly across from the Berlin Cathedral, appears from the exterior to be just another ordinary luxury hotel. Once you enter the hotel, nothing prepares you for the sight of the giant cylindrical Aquarium towering 25m (82 feet) smack in the center of the lobby.
The AquaDom was opened in December 2003. It cost about 12.8 million euros. The acrylic glass cylinder was constructed by the U.S. company Reynolds Polymer Technology. The outside cylinder was manufactured on-site from four pieces; the inside cylinder for the elevator was delivered in one piece. The Aquadom is the largest acrylic glass cylinder in the world, with a diameter of over 11 meters, built on a 9 meters tall concrete foundation. Filled with about 900,000 liters of seawater, it contains some 2600 fish of 56 species. The feeding of the fish and the cleaning of the fish tank is performed daily by divers.