From Wikipedia:

Prora is a beach resort on the island of Rügen, Germany, known especially for its colossal Nazi-planned touristic structures. The massive building complex was built between 1936 and 1939 as a Kraft durch Freude (KdF) project. The eight buildings are identical, and while they were planned as a holiday locale, they were never used for this purpose. The complex has a formal heritage listing as a particularly striking example of Third Reich architecture.

Dr. Robert Ley envisioned Prora as a parallel to Butlins - British "holiday camps" designed to provide affordable holidays for the average worker. Prora was designed to house 20,000 holidaymakers, under the ideal that every worker deserved a holiday at the beach. Designed by Clemens Klotz (1886-1969), all rooms were planned to overlook the sea. Each room of 5 by 2.5 metres (16'5" x 8'3") was to have two beds, an armoire (wardrobe) and a sink. There were communal toilets and showers.

Hitler's plans for Prora were much more ambitious. He wanted a gigantic sea resort, the "most mighty and large one to ever have existed", holding 20,000 beds. In the middle, a massive building was to be erected. At the same time, Hitler wanted it to be convertible into a military hospital in case of war. Hitler insisted that the plans of a massive indoor arena by architect Erich Putlitz be included. Putlitz's Festival Hall was intended to be able to accommodate all 20,000 guests at the same time. His plans included two wave-swimming pools and a theatre. A large dock for passenger ships was also planned.