At the time of the colonial foundation the Romans had levelled the hilltop to create a massive, steeply elevated platform some 30,000 square metres in size on which were placed a cluster of quintessentially Roman buildings: a vast, dominating colonnaded forum, a grand judicial basilica, and two great temples, one most likely a Capitolium, the other perhaps intended for the imperial cult.

Alberti seems to have surveyed the city by "triangulation" from a number of points, not just from the central Capitolium.