The 12 m tall structure has a diameter of about 8 m and was topped in antiquity by a weathervane-like Triton that indicated the wind direction. Below the frieze depicting the eight wind deities---Boreas (N), Kaikias (NE), Apeliotes (E), Euros (SE), Notos (S), Lips (SW), Zepyhros (W), and Skiron (NW)---there are nine sundials. In its interior, there was a water clock (clepsydra), driven by water coming down from the acropolis.
In early Christian times, the building was used as the bell tower of a Byzantine Church. It was partly buried in the ground until it was fully excavated in the 19th century by the Greek Archaeological Society.