The Lions Gate at Mycenae: the fortress of Agamemnon (Troilus & Cressida).

Homer cites Mycenae as Agamemnon's base, but Theseus probably had a similar stronghold at the Acropolis of Athens. This photo was taken by Andreas Trepte,www.photo-natur.de. Courtesy of the Yorck Project, under Creative Commons Attribution-Share- Alike License (Wikipedia)