theseion

from The Century Dictionary.

• noun A temple or sanctuary of the Athenian hero-king Theseus, especially a temple built in Athens, about 460 b. c., to receive the bones of Theseus, then brought home from Scyros; at the present time, specifically, a beautiful hexastyle peripteral Doric temple of Pentelic marble, dating from the second half of the fifth century b. c., still standing in Athens at the foot of the Acropolis and Areopagus.