The 10,000-room Prora Hotel on Rügen island in Germany. Stretching for 2.7 miles, this holiday resort for tourists which was then a dream of Adolf Hitler, was started in 1936 and built by about 9,000 workers.
Just on the verge of completion at the beginning of the second World War in 1939, it was abandoned and none of the 10,000 rooms have been used in the past 70 years.
The buildings still stand today with their deteriorating interior as a reminder of the architecture of Nazi Germany.
This is what the interior of the hotel looks like now: