The countryside of Siphnos is characterized by a large number of monumental strong circular-plan structures, known as towers. Built on a variety of terrain, and in an impressively high density, they date mainly to the end of 4rth and the 3rd century B.C. and had multiple uses in their long, in many cases, function.
In the survey area of the Program “Siphnos & Beyond”, which extends from the bay of Kamares all the way to Vathy, 22 towers are located on as many farms. Ten of these towers account for farms of a surface area of 1km2 (100ha) providing ideal conditions for the cultivation of olive trees. It is estimated that during Hellenistic times (from 4th century B.C. onwards), this area. This area could supply oil to 1,500 people, whose feeding needs were estimated to require the import of 460 tonnes of grain worth 62,000-124,000 drachmas per year, an amount which seems to have been derived from metal mining. Twelve of the towers in the same area are located near mining sites with remnants that attest to intensive metallurgical activity. It is estimated that 7,600 tonnes of iron were annually extracted from the surface. It has been argued that at that time a tonne was worth between 8 and 16 drachmas.
According to epigraphic, numismatic and literary evidence, at the time when most of the towers were founded (3rd century B.C.), Siphnos had close links with Ptolemaic Egypt. The Ptolemies were able to ensure safe passage through the Aegean and to supply Siphnos with grain in exchange for metals. Because of the Ptolemaic demand for iron, a “communal” system of living and working developed in the island which was established, maintained, used and probably became property of all the inhabitants of Siphnos. When the Ptolemaic need for iron diminished at the end of the 3rd century B.C., this system declined.