The tholos of the Sicyonians was probably the oldest construction, dating to ca 580 B.C. and built right after the First Sacred War at the instigation of the tyrant of Sicyon Cleisthenes, who was the most prominent leader in that war. It measured 6.3 meters at the base and 3.54 meters at the floor level and was surrounded by a colonnade consisting of 13 Doric columns and a Doric architrave. The cella was circular, made of ashlar masonry with a single door. The height of the walls was 4.04 meters. The shape of its roof is conjectural as nothing has been preserved.