Just outside the old town is located this abbey (second half of the XII century), wrapped in the forest. Situated on Monte Santa Croce, in isolated position, is a very fascinating and not very known Romanesque monument, probably the work of craftsmen from Lombardy. For its construction was used a lot of material coming from the nearby Roman city of Sentinum, such as the mighty columns of stone. Outside is to see the fifteenth century bell-tower and the arch of the stone portal decorated with geometric and floral motifs, which stands on the capitals carved with the repertoire of the medieval bestiary. Inside, the columns have capitals of various shapes with floreal, animal and human motifs (second half of the XII century). Important are the frescoes by the school of Fabriano of the fourteenth century decorating one of the apses, representing the “Vita leggendaria di S.Tommaso apostolo”. Other frescoes are on the columns, among which we can see a “Santa Scolastica” and “Sant’Alberto”, and in a chapel there is an exceptional wooden “Paliotto” of the seventeenth century decorated in gold, probably a work of the French engraver Leonardo Scaglia.