How it began
The tower stands in the Roman Agora of Athens. According to Vitruvius and Varro it was designed by the astronomer Andronicus of Cyrrhus, about whose life very little is known. Its date is uncertain. From the style of its sculpture it is usually put at around 50 BCE, and it was finished by then at the latest, since Varro mentions it in a work of about 37 BCE. Another suggestion links it to the generosity of Attalus III of Pergamon, which would make it earlier.
How it works
The tower is octagonal, built of Pentelic marble, 12 meters tall and about 8 meters across. Each of its eight faces looks toward one of the winds, shown in relief at the top, and carries a sundial cut for the hours that face is in the sun. On the roof stood a bronze Triton holding a rod that turned to point out the wind. Inside, a water clock ran on water piped from a spring on the Acropolis into a tank at the back. The channels and holes in the floor remain, but the mechanism is gone.
What changed first
The height of the tower was chosen so that the sundials and the vane could be seen from the market. People in the Agora could read the hour and the wind from one building. In the words of one historian quoted in the sources, citizens could orient themselves in space and time. It is not clear whether the reading of the water clock could be seen from outside, and it may have been necessary to go in. The clock may have shown a calendar and the movement of the stars.
What lasted
The building has been used almost without a break, as a church or baptistery in late antiquity and as a lodge of Qadiri dervishes from 1751 to 1821, which is why it stands nearly intact. James Stuart and Nicholas Revett surveyed it in 1751 to 1754 and published measured drawings in London in 1762, making it widely known. The Greek government news service describes its vane as the oldest known in the Western world.
Where it stands today
The tower still stands in Athens with its original stone roof of 24 slabs. The bronze pointers of the sundials have been replaced with modern ones set in the old holes. The Athens Ephorate of Antiquities cleaned and conserved the structure between 2014 and 2016. Athenians call it Aerides, the winds.
