Here you can see the largest construction that the Third Reich were working on in the 1930's. Robert Ley was the mastermind behind this nearly 5km-long complex of buildings, built under the auspices of Kraft durch Freude (KdF - Strength Through Joy) workers association, part of the Deutsche Arbeits Front (DAF).
These complexes of buildings were intended to house up to 20,000 people - average german workers - providing them a view of the sea, 5 x 2.5 meter rooms with 2 beds, and armoire, and a sink (communal toilets and showers).
You can read more about it here:
http://www.thirdreichruins.com/prora.htm
http://en.wikipedia.org/wiki/Prora