The tower at Agios Petros on Andros dates from the Hellenistic period
(4th-3rd centuries BC) and is one of the best preserved towers in the Cyclades.
It is cylindrical, made of local schist, with a diameter of 9.40 m. at the base
and a height of almost 20 m. A winding staircase leading to five, at least, storeys,
is preserved inside the building. The tower is located at a commanding position
over the plain of Gavrion
and has a wonderful view to the sea. Around the monument are preserved installations
for the extraction of metals (copper) used as late as the beginning of the 20th century.
There is evidence, though, of similar activity in antiquity. The tower was evidently
used for the control of the surrounding land and the sea.