Between the Via Flaminia and Tiberina are many towers like those of old and new Procoio. Over the centuries an impressive number of quarries has swallowed up settlements, necropolis, castles and watchtowers. In Procoio estate two important watchtowers, placed on parallel hills, are preserved. This estate belonged in the Middle Ages to the monastery of San Paolo under the name Precodium Grotta dei Greci, before moving to the Cesi family, then the Ruspoli and the Boncompagni. On top of a hill are the remains of an ancient square tower that has only relatively recently collapsed.