Situated at the top of a steep hill, the Dacian fortress of Căpâlna was built in the second half of the 1st century BC as a military defense, guarding the entrance from the Sebeș Valley to the capital of the Dacian kingdom, Sarmizegetusa Regia.

On the higher level terrace, at the highest point, an observatory tower existed.

A tower house (9.5 m x 9.5 m) was positioned strategically near the main fortified gate.

A second gate positioned through the Sebeș Valley was blocked after the first war, sometime after 102 AD.

The fort follows the architectural principles of the Dacian Fortresses of the Orăștie Mountains; the wall being the typical murus Dacicus.