The Hall of the Altars is a rectangular area in the Sacred Area of the Republican Temples, opposite the Temple of Hercules. Four tufa altars were found here. They belong to the republican period, and at least one altar is very old (from the middle of the third century BC or older). Only the east part of the area (to the east of the altars) had a roof, supported by piers. The present wall of the hall is of Trajanic opus mixtum.
Meiggs has suggested that the altars were in the care of the Sodales Arulenses, a religious guild documented at the end of the second century AD. Arula is Latin for a small altar.