Situated on a limestone outcrop of Eocene age to the west of the canyon of the Rio Vero in the Sierra y Cañones de Guara Natural Park, the village grew up around a castle and the Collegiate church of Santa Maria, which was consecrated in 1099.

The name of the village comes from the Arabic al qaçr for "fort" or "castle" (renamed as Alcazar in Spanish). The castle became the main defense point of the nearby city of Barbastro.

Since Alquezar is situated in the Sierra y Cañones de Guara Natural Park, there are various campsites in the local area to cater outdoor pursuit enthusiasts. Popular activities include canyoning, walking, rock climbing and abseiling, as well as ornithology (since eagles nest on the steep faces of the Rio Vero canyon).

The surrounding area to the south towards Barbastro, in the direction of the flatter Ebro basin, is part of the Somontano, an area known for its fine wines. There are more than 60 limestone caves with prehistoric cave paintings in the surrounding area, which has led to the region being declared a World Heritage Site by UNESCO in 1998. A good example is the cave at Arpan on the A-2205 road heading north towards Barcabo.