The tiny Temple of the Round Altar is to the south-west of the Temple of Hercules, in the Sacred Area of the Republican Temples. To the first, republican phase belong remains of a podium of large tufa blocks. At the end of the first century AD a brick cella was built, and a pronaos with two columns between piers. The temple was decorated with marble, the remains of which have been attached to the wall opposite the temple. The (Trajanic) round altar with cupids that gave the temple its name is now in the museum.