This chapter seeks to advance interpretation of two major building complexes unearthed beneath the Lateran Basilica.The earliest structural evidence exposed is interpreted part of an Augustan age suburban villa, likely a single property positioned between the via Tusculana and via Asinaria. The first, residential part of this complex can only be partially seen below the structures of the Castra Nova Equitum Singularium and the so-called ߢTrapezoidal Buildingߣ. These residential quarters lay to the west in the direction of the main road (via Tusculana) and shared its alignment. The eastern half of the complex was less lavishly appointed; it was structured around a pillared courtyard (lying below the point where the principia of the Castra Nova was subsequently built), oriented along a suburban roadway and probably in close proximity to the pars rustica of the villa. The second part of the paper offers a hypothesis for the Trapezoidal Building itself and argues that it might have served as the valetudinarium (hospital) of the Castra Nova.