The entire ensemble was composed of 2 churches, at least one martyrium, several Hypogeums as well as a subterran rotunda with a complex interpretation.
[4] The most massive element of the complex is a church with nine (then eleven[2]) naves, from which the largest mesures 12.80 metres[5] and eleven bays whose pillars have Corinthian capitals, the barrels of the columns are made out of green marble and the bases out of white marble.
The most important element of the known appendices is located in the southwest : It is a subterran rotunda, having an interior diameter of 9.15 metres [6] with a cupola.
Two symmetrical stairs,[7] vaulted and in square[4] permit the access ; the ceiling is still partially covered with tubes of terracotta.
The corridor is 10.40 metres long and forms an angle before giving access to the underground room.