Shrine of Zeus Olympios
From Project Athinai
The shrine dedicated to Zeus Olympios was located in a cave in the northwest part of the Akropolis Rock, above the Paved Court. It was also known as the Olympion (not to be confused with the Olympeion, the huge temple of Zeus).
The eschara (bench) of Zeus Astrapaios stood in front of the cave
There was a leveled terrace in front of the cave. Even during the Roman period, remnants of the Pelargikon wall still contained this terrace.
There was another sanctuary dedicated to Zeus Olympios along the Ilissos river to the southeast of Athens.
Travlos, John, Pictorial dictionary of Ancient Athens, Books that matter, New York, 1971, p. 91, 93