Although it had been called Grotte di Traiano, or Trajan Caves, by the more erudite inhabitants of the area, the catacomb wasn't rediscovered until 1900. And it wasn't until the 1940s that archaeologists excavated most of the galleries, which were also used as bomb shelters during the Second World War. In 1996 and 1997, while work began to make the catacombs accessible to the general public, a small funerary basilica used mostly for worship was discovered in the immediate area.

The catacomb spreads out along a straight 22 m-long corridor that penetrates the hillside and runs 7 metres lower than the surrounding countryside. Two galleries branch off from either side of it, one of which is semi-circular, and they are about 1.5 m wide with low, flat ceilings. Loculi of various sizes were carved into the walls. Some were covered with large tiles and many contained simple little terracotta lamps as burial effects. Formae, or graves, were also dug into the floor and covered with large tiles bearing circular marks carved into them before they were fired. There are no inscriptions bearing the name of the deceased and this has lead scholars to believe the catacomb may have belonged to an illiterate sect. The lamps and other material would indicate the area was frequented between the 4th and 5th centuries.

The ancient name for these places is coemeterium, from the Greek word for dormitory. The word catacomb, which was at one time used only in connection with the large Complex of St. Sebastian along the Via Appia, was later used to describe all underground Christian burial places.