The architecture of the peristyle is characterised by a colonnaded portico composed of thirty-two marble or grey granite columns, placed evenly on an Attican base of white marble. The corner columns, placed on raised bases, are in Breccia di Sciro or Breccia di Settebasi, stone from the Greek island of Skyros. Its name results from its use in large quantities to decorate the Villa dei Sette Bassi, located in the Roman countryside and belonging to Septimius Bassus, praefectus urbi at the end of the 2nd century AD.
The Corinthian style capitals would have supported an architrave, on which the sloping pitched roof structure that covered the portico sat.
