Birtvisi, Medieval fortress in Kvemo Kartli, Georgia

Birtvisi is a ruined medieval fortress occupying a naturally fortified rocky massif of Eocene porphyrites and tuff breccias in the Algeti valley. Its roughly 1 km2 complex combines inaccessible cliffs and narrow passages with defensive walls, towers and a gateway. The cylindrical Sheupovari tower stands on the highest rock, and rock-cut steps, a reservoir and an aqueduct survive among the remains.

In 1038, Georgian nobles Liparit and Ivane Abazasdze took control of the fortress from an Arab emir and secured Georgian rule in the region. This takeover marked a turning point in local control of the important trade routes.

The fortress shows how medieval Georgians built and used their strongholds in difficult terrain. The towers and walls were positioned so that residents could control and watch over their surroundings.

The customary approach starts near the village of Tbisi, not Partskhisi, and passes through a rock passage called the "Devil's Footprint" before reaching the main complex. The site covers about 1 km2 of cliffs and narrow passages, so allow time for steep walking between the walls, towers and reservoir.

The highest tower, called Sheupovari, perches on an isolated rock and offered its owners an unobstructed view over the entire gorge. From here, guards could track all activity on the trade routes below.