Ertij Fort, Medieval fortress in Arpi, Armenia.

Ertij Fort is a medieval Armenian fortress on a hill by the village of Arpi in Vayots Dzor Province. It is protected on three sides by natural terrain. Inside are the remains of a water reservoir and dwellings, broken khachkars, and the foundation of a defensive wall.

Built during the 13th century as a strategic defensive stronghold, Ertij Fort served to protect local communities and control regional routes during periods of conflict and territorial disputes throughout Armenian history.

The fortress represents an important example of medieval Armenian military architecture and serves as a cultural heritage monument that reflects the region's historical resilience and traditional construction techniques.

Visitors can access Ertij Fort via roads leading to Arpi village, with the site offering educational opportunities to explore medieval Armenian defensive structures and panoramic views of the surrounding landscape.

Below the hill, on the slope directly beneath the fort, lie the remains of the abandoned village of Ertij, whose ruined houses gave the fortress its name. In the late 19th and early 20th centuries, when Tajiks lived in the village, the fort was known as "Shirali Khan's fortress", according to Kajberuni.