The amphitheater at the Spartan acropolis was built by the Romans in 50 B.C. and there are also Roman walls around the hilltop. Lower down and covering a larger area are Byzantine walls in ruins. Both of these sets of walls protected a citadel that was post-Spartan.
There are only two ancient Spartan structures that have been uncovered: the Temple of Athena Chalkioikos, located on the Acropolis and The Temple of Artemis Orthia located east of the Acropolis near the Eurotos River. Chalkioikos was constructed no later than 500 B.C, because artifacts from that time have been found in the ruins.