An old wall town on the left bank, half way up the Cesano Valley. The town is built on a small hill slope while the borgo itself stands on the main road below it.
This pleasant town bears the name of an abbey which was founded by Benedictine monks in the early Middle Ages and built using materials from the destroyed Roman town of Suasa Senonum which stood nearby. The abbey, together with the extensive surrounding area which also belonged to it, had a long history as an independent territory right up to the 19^th century. Among its various commendatory abbots was Giuliano Della Rovere, who later became Pope Julius II. Passing under the entrance way leading up to the ancient castle we find the austere 16^th Century Palazzo Della Rovere, which now houses three museums - an archaeological museum, a museum of African ethnography and a natural history museum. There is also a 19^th Century theatre, il Teatro "M. Tiberini", with an elegant auditorium and boxes, entirely decorated with Neo-classical and Liberty style designs. A sturdy castle once stood above it on the top of the hill but this was destroyed twice and later rebuilt as an annexe to Palazzo Della Rovere below it. The abbey of San Lorenzo stands in the borgo below. It is a fine example (even though part of it fell into neglect and was later rebuilt) of Romanesque style and has a presbytery and triple apse, with a large crypt beneath it. The attractive fortified villages of Montalfoglio (393 m) and San Vito sul Cesano (353 m) also form part of the district of San Lorenzo, each still surrounded with sturdy escarpment walls.
The archaeological area of the ancient settlement of Suasa Senonum stands on the right bank of the Cesano river, in the district of Castelleone di Suasa (in the province of Ancona). This was founded by the Gauls, then ruled by the Romans and finally destroyed by Alaric's Gothic army in 409 AD. The remains of the amphitheatre and of a patrician villa decorated with splendid mosaic floors can still be seen today.