In the middle of Parnitha National Park (only a few kilometers from Athens) lie the ruins of a villa owned by the dictator Papadopoulos, head of the military junta that governed Greece from 1967 to 1974.
The villa was immediately looted after the junta fell and he went to jail. Anyone can reach the site now (which features also a heliport and a deserted military camp) by foot or by bicycle. It is unknown why the Greek state hasn´t turned it into something useful like a mountain refuge (it is in 1100m alt).
See the place in Wikimapia