Horologion of Andronikos Kyrrhestes (Tower of the Winds) is an octagonal marble clocktower in the Roman Agora in Athens that functioned as a horologion or "timepiece". It is considered the world's first meteorological station. Unofficially, the monument is also called Aerides, which means Winds. The structure features a combination of sundials, a water clock, and a wind vane. The Tower of the Winds was built by the astronomer Andronicus from Cyrrhus of Makedonia in the first half of the 1st century BC. At the top of each side are embossed the winds with their symbols with their names engraved. Outside there were sundials, while inside there was a hydraulic clock.