Just outside Porta Maggiore in Rome, hidden seven meters below the current level of Via Prenestina, lies the Underground Basilica, a fascinating complex from the 1st century AD, accidentally uncovered in 1917.
It is the oldest example of a basilica structure found so far in Rome, a floor plan with three naves and an apse at the end of the central one, which would become one of the canonical forms of Christian buildings. However, the Basilica of Porta Maggiore is a pagan temple most likely dedicated to Pythagorean cults, still shrouded in mystery today.
The complex consists of an access corridor, a quadrangular vestibule with a pavilion vault pierced by a skylight, and a main basilica-type hall divided by six pillars into three naves covered with barrel vaults. The precious decoration of the stuccoes miraculously preserved, depicting mythological scenes, paintings, and mosaics on the floors stands out.
