In the immediate outskirts of Poggio Mirteto lies the ancient graveyard and church of Saint Paolo, part of the original structure of ann important castle which was founded between the thirteenth and fouteenth centuries. The small building presents a single hall structure  with four bays which hold the ogival arches. Owing to the numerous  restorations which the church underwent during the centuries, the original structure has been greatly modified. Despite these interventions, however, the precious and interesting works of art which the building contains are in a poor state of conservation. On the left hand-side of the counter façade one can see the most important painting, a fresco which represents "L'incontro tra i tre vivi con i tre morti"; the opera is described by means of an inscription in dialetical metrics, a type of writing which slowly vanished during the centuries. The apse contains a fresco of the first half of the sixteenth century which depicts the coronation of the Virgin amidst singing angels.