The horizontal facade is embellished by a round window and two magnificent "bifore" (a bifora is a window divided into two by a small column), among the most ancient example of this architectural element, which will become widespread in the region in the following two centuries.
The entrance portal is surmounted by a round arch, supported by square stones with low-relief sculptures, especially zoomorphic figures typical of the early Middle Ages: strange lions, dragons, griphons, doves, are also to be found inside the church, creating an almost spectral atmosphere.
The low-reliefs are important for correctly dating the church. It seems they were already in place in 1080, while after that date the portal was made (about mid-13th century), possibly after an earthquake that destroyed the original portal, as well as the attached monastery, whose ruins are still to be seen outside the church. To a much later date belongs the belltower, also probably built on the remains of a previous building.
The inside is parted into three naves, divided by six arches on each side; the central nave ends into a semi-cylindrical apse, in the Lombard style. In the apse there is a very beautiful fresco, partly damaged, going back to the Renaissance (15th century), representing Christ inside an almond-like circle with the Virvin Mary, St John the Baptist and the so-called "San Giovannino", which is probably a Child Jesus. The author is unknown though he clearly belonged to the same school as Andrea Delitio, the most important Abruzzese Renaissance painter.
A very peculiar presbyterium (which was the area in the early Christian temple reserved to those who already had received baptism) is placed on a higher level, connected to the lower part of the church by six steps, which is built over a large square crypt which occupies two-thirds of the building. The crypt existed probably before the church was built, and may belong to the early centuries of the Christian era.