On September 25, 1364, by Albornoz's decision, they started to build the fortress inside Orvieto, although the town was already a “natural stronghold,” indeed there were no external walls precisely thanks to its position on top of a tuff cliff. The building was meant as a defense against military attacks, but, above all, as a symbol of the central authority and the Pope's strength. The project was probably the work of Ugolino di Montemarte (1320 ca. – 1388), a military architect, a Count, and more than that, a Guelph. The fortress had a squared shape, was encircled by a ditch, and had drawbridges. There remains very little of it, however, since in 1390 the stronghold was assaulted and destroyed by the inhabitants themselves.
It would be rebuilt in the years 1450-1457 by decision of Pope Nicholas V, adding the circular tower. In the 16^th century another Pontiff, Clement VII – who also commissioned the Well of Saint Patrick - had the structure strengthened.In the 19^th century, anyway, the fortress lost its military function forever. The ditches were filled with dirt during the works on the funicular railway, and a modern amphitheater was built inside to host plays and shows.
Already visible is Porta Postierla, one of the town gates, next to the former fortress. Of which, there now remain the external walls and the towers, while the whole area has been changed into a public park: a fantastic place to take a break, relax, and enjoy the landscape