Noteworthy among the buildings within the ancient citadel is a small tetrastyle temple, variously ascribed to Jupiter and Minerva, the portico supported by six monolithic columns of cippolino, four being in front.
The temple, which is entirely of Pentelic marble, the Acro- is amphiprostyle tetrastyle, with fluted Ionic columns, polls.
A tetrastyle pedimented Roman Doric porch sits to the center, its unjointed columns hewn from menhirs taken from a nearby druids ' temple.
Gregorio is built into a Roman tetrastyle Corinthian temple, two columns of which and the cella are still preserved; the site of the Roman theatre can be distinguished; and the church and convent of the Annunziata (with two fine cloisters and a good fresco by Cola d'Amatrice in the refectory) are erected upon large Roman substructures of concrete, which must have supported some considerable building.