Lake Marathon

Built between 1926 and 1929 to give Athens a reliable water supply, the dam closed the valley of the Charadros and created a lake of some 2.5 square kilometres in the hills below Mount Parnitha. Its designers faced the entire downstream wall in Pentelic marble, the same quarry that supplied the Parthenon, which makes it the only marble-clad dam in the world; a small copy of the Athenian Treasury at Delphi stands on the crest as a monument to the engineers. The lake supplied all of the city's water for decades and remains part of the network, so swimming and boating are forbidden and the shoreline is fenced in most places. The road along the top of the dam is open, and pine-covered slopes with picnic spots run around the eastern side.

What you actually see

• The marble dam - the white downstream face and its crest walkway.
• The treasury replica - a scaled copy of a Delphi building on the dam.
• The reservoir - still water below wooded hills, best in the morning.
• The pine slopes - shaded viewpoints along the approach roads.

When to go

Autumn to spring, when the water is high and the hills green; late summer drops the level and exposes bare shoreline. Mornings are calmest for reflections.

Honest expectations

This is working infrastructure, not a leisure lake: no swimming, no boats, fences along most of the water, and no visitor facilities. The dam itself is the sight, and half an hour covers it unless you walk the surrounding tracks.

Nearby

Schinias beach and the Marathon plain lie east; Mount Parnitha rises to the west.