On the Palatino, the Domus was the emperor's private residence in the imperial palace. It was built on two levels, with rooms leading off a peristilio (peristyle or porticoed courtyard) on each floor. You can't get down to the lower level, but from above you can see the basin of a big, square fountain and beyond it rooms that would originally have been paved with coloured marble.
In 2007, a mosaic-covered vaulted cavern was discovered more than 15m beneath the Domus. Some consider this to be the Lupercale, a cave believed by ancient Romans to be where Romulus and Remus were suckled by a wolf.
Also here are the Aula Isiaca and Loggia Mattei, both accessible with the SUPER ticket. The former is a frescoed room from a luxurious Republican-era house, the latter a Renaissance loggia decorated by Baldassarre Peruzzi.
