Basilica di Generosa is a ruined palaeochristian basilica over the Catacombs of Generosa, which are to be found on the Via delle Catacombe di Generosa. This is a dead-end street off the Via della Magliana in the Portuense district, south-west of the suburb of Trullo.
There is very little visible above ground.
At about the year 300 a small Christian catacomb was developed here in an abandoned pozzolana quarry, and according to legend three martyred siblings named Simplicius, Faustinus and Beatrice were enshrined here at about that time. The name Generosa came from the owner of the land in which the quarry had been dug. As a result of the development of the veneration of the martyrs, Pope Damasus built a basilica over the entrance of the catacombs around the year 370.
This had a surprisingly short existence, as it is thought that it was abandoned about the year 600. The catacomb remained visitable until at least 682, when the relics of the martyrs were transferred by Pope Leo II to a church called San Paolo near the present church of Santa Bibiana. They then fell out of use and were lost.
They were rediscovered by chance in 1868 and part of the basilica was excavated. Fortunately, a fragment of its dedicatory inscription was discovered which enabled the catacombs to be positively identified. However, the basilica was only fully excavated in 1980.
The catacombs are accessible, but not regularly open. Guided tours sometimes take place.
The archaeological survey revealed a building with a north-south orientation which had been partly excavated from the hillside, being only accessible via an entrance from the west. The building, 20 metres long and about 14 metres wide, was divided into a naves with aisles of different widths and had a narthex or portico to the south. The apse has an irregular profile and was offset from the longitudinal axis of the building, the latter being slightly oblique to align to the shrine of the martyrs already within the catacomb. To the right of the apse was a door, the introitus ad martyres, by which visitors entered the main gallery of the catacomb to visit the shrine.
The basilica was itself a burial place until the first decades of the 6th century. Under the floor, in fact, have been found numerous graves, dug directly in the clay and, in some cases, covered with tiles laid flat. Some burials were placed near the apse in tombs built of brick and closed with marble slabs, which served as the floor of the church itself.