Birtvisi
Tetri Tsqaro Municipality, Georgia · built 1000
Birtvisi Fortress, commonly known as Birtvisi, is a ruined medieval fortress within the Birtvisi Natural Monument in Tetritsqaro Municipality, Kvemo Kartli, Georgia. It occupies a naturally defensible rocky massif on the southern slopes of the Trialeti Range, near the villages of Tbisi and Partskhisi. The medieval structures, defensive walls and rock-cut steps form part of the natural and historical complex protected by the natural monument.
Fort data from Wikidata (CC0). Summary from Wikipedia (CC BY-SA).