Birtvisi (fortress) built
1000 CE.
Shown on the map at 41.609°, 44.539°.
Birtvisi Fortress (Georgian: ბირთვისის ციხე), commonly known as Birtvisi (ბირთვისი), 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.
Text from the Wikipedia article Birtvisi Fortress, licensed CC BY-SA 4.0.