There are considerable remains of perhaps pre-Roman polygonal walls - in one place a piece of this walling has masonry of rectangular blocks superposed, with an inscription of two of the Roman municipal magistrates (quattuorviri).
The rock above the town was included within the polygonal walls: but Totila fortified, not this rock, but the amphitheatre, which remained the citadel until 1364, when Cardinal Albornoz destroyed it and erected the present Rocca, which was enlarged by Pope Nicholas V.; it is now a prison.
Remains of the city walls, in the polygonal style, still exist, to which Roman gates were added.
The polygonal terrace walls, which exist in considerable numbers in the district, are shortly described in Romische Mitteilungen (1903), 147 seq., but require further study.
But these were exceptional, the usual material of an altar was marble, and its form, both among the Greeks and Romans, was either square or round; polygonal altars, of which examples still exist, being exceptions.