These are the huge buttresses in the centre of the picture. It’s the Emperor Septimius-Severus who gave that grandiose complex to the Palace, after a severe fire of the buildings in 191. Actually the construction is the extension of the south-east angle of the hill and demanded powerful arcades to sustain the whole building. A belvedere offered a splendid sight over the Circus Maximus; The Baths of Septimius-Severus (Balneum Palatii) were part of a complex close to the Pulvinar, or imperial loggia in Domitian’s Stadium.

A closer view of the Baths. In the foreground the Septizodium.