The old town of Perugia is built on an acropolis at a height of about 450 m above sea level. Its highest point, Porta Sole, stands at 494 m; this makes it the most densely populated Italian town among those located at more than 250 metre altitude. The old town was built around this spot and on the hillslopes starting from there, forming an acropolis and five medieval boroughs extending across five gates. The original Etruscan city walls, 3 km long, were extended in the thirteenth and fourteenth century with a new and final walling about 9 km long, which is almost totally intact and encompasses a surface of 120 hectares.
The historic boroughs are: Porta Sole, Porta Sant’Angelo, Porta S. Susanna, Porta Eburnea and Porta S. Pietro, which for centuries corresponded to the respective sections of the rural land, governed by the city ever since the Commune government was established. Each borough is centred around a main road, or Corso, onto which the winding alleys converge; there are convents, bell-towers, basilicas, churches, oratories, chapels, stately homes (about a hundred), smaller villas and row houses in the alleys.