The Tower of the Winds or the Horologion of Andronikos Kyrrhestes is an octagonal Pentelic marble clock tower within the Roman Agora in Athens that functioned as a horologion or clock.
The structure features or did a combination of sundials, a water clock, and a wind vane.
It was supposedly built by Andronicus of Cyrrhus around 50 BC, but according to other sources, might have been constructed in the 2nd century BC before the rest of the forum.
The water clock may have taken the form of a waterwheel.
The roof is a series of triangular slabs locked in place by a circular keystone.
Around the periphery is represented the eight winds.