The first time we visited Athens the tower we closed, but it was open the second time. It is found in the more modern Agora – the Roman Market area of Athens. The tower is arguably the world’s first weather station, contains a sundial, water clock and wind vane. The tower was build sometime between about 200BC to 50 BC, so is at least 2000 years old, and is in remarkable condition (well it has just been restored).
It is called the Tower of the Winds because each face should a different wind. The Roman Agora in Athens is worth a visit if you an extra hour or two to spare.