The archaeological site of Pyrgos Ragiou occupies a low hill in the middle of the Ragio-Kestrini plain, near the old estuary of Kalamas River. The site had a continuous use from the Middle Paleolithic period until the times of the Ottoman rule. The fort is believed to have been part of one of the military bases which, according to Thucydides, ancient Corkyra established along the Thesprotian coast during the first years of the Peloponnesian War.
During the 5th century BC the hill was fortified with a strong isodomic wall, still well preserved, encircling an area of 3.000 sq.m. Later modifications of the late Classical and Hellenistic periods in polygonal style can be traced at the western side of the fortification. The wall was reinforced with rectangular towers and indentations. In antiquity the main gate of the fortified site was at its southern side, while there was also another narrower entrance to the north.
Building remains of the Classical and Hellenistic periods are limited within the fort due to the military character of the site. Among them stands out an impressive rock-hewn cistern for the collection and storage of rainwater and a rectangular curving on a projecting rock -known today as “Aga’s throne”-, the use and construction date of which remain speculative.
The habitation of the site was more systematic during the Οttoman period. This is when a two-storeyed building was constructed right above the northern tower of the ancient fortification wall: the Tower (Pyrgos), to which the site owns its name. The Tower belongs to the architectural type of “koulia” or “kula” which, along with the type of towerhouse, was quite common in the whole Balkan area during the Οttoman period. It was a building of defensive character with no entrances or other openings on the ground floor. The only entrance is situated at a higher level and was accessible via a wooden drawbridge. The windows are small and absent from the ground floor. For the efficient confrontation of the enemy, there are gun slits on every wall, as well as a hopper shaped opening right above the entrance for pouring hot oil or water down on attackers.
The ottoman Tower has been restored to its original form and currently operates as an exhibition hall.