Acropolis of Serres, Archaeological site and citadel in Serres, Greece

The Acropolis of Serres is an ancient fortress perched on Koulas hill with preserved defensive walls, multiple towers, and ruins spanning various historical periods. The structures spread across the hilltop and reveal layers of fortification work built over centuries.

The citadel was built in the 9th century, probably under Emperor Nikephoros Phokas, on the foundations of a fortress of the 7th–6th centuries BC. After 1204 it passed to the Frankish Kingdom of Thrace; in 1206 the Bulgarian tsar Ioannitsa destroyed parts of the walls and the acropolis, which was rebuilt in 1208. The Tower of Orestes dates to 1350, attributed to Serbian ruler Stefan Dušan.

The Byzantine church of Saint Nicolas sits at the northeast end and shows a rare three-part interior layout with an underground chamber below. This building reveals how religious life was woven into the fortress.

The site is open year-round with no entrance fee, so you can visit freely at your own pace. Wear sturdy shoes since paths across the hilltop and around the ruins are steep and uneven in places.

The Tower of Orestes, the only survivor of the four towers the French Capuchin monk Robert de Dreux recorded along the wall, was the defenders' last refuge if the acropolis fell. Its name comes from a walled-in inscription naming Orestes as its builder.