Regio X was centred on the
Palatine Hill. In extent, the region largely followed the contours of the Palatine, and so was bordered by the
Velabrum on the north west, the
Circus Maximus to the south west, the
Via Sacra on the north east, and on the south east, a street where the modern Via di San Gregorio is now situated. A measurement taken at the end of the 4th century recorded that the perimeter of the region was 11,510
Roman feet (approximately 3.4 km), making it the second smallest of the Augustan regions. The hill itself is dominated by a series of imperial palaces, which were the residences of the emperors and their families whilst they were lodged in the city. The most prominent of these was the vast
Palace of Domitian, with its three principal wings: the
Domus Augustana, the
Domus Flavia, and the Hippodrome of Domitian (in reality, a private sunken garden). Earlier palaces had been created by the emperors
Augustus (the
Domus Augusti) and
Tiberius (the
Domus Tiberiana), both of which were preserved by later emperors. Later, the
Domus Severiana was added by the emperor
Septimius Severus, who also constructed the
Septizodium (or the Temple of the Seven Suns) adjacent to it. The hill also possessed several other temples. First was the
Temple of Apollo Palatinus, built by Augustus, to which was attached a library (the
Bibliotheca Apollinis). The Temple of Apollo was situated next to the much older
Temple of Magna Mater. Also here, according to the 5th century
Notitia, was the
Temple of Jupiter Victor, which is assumed to have been situated near the entrance of Domitian's Palace. This region also contained a number of sites that dated back to Rome's mythical past. Chief amongst these was the
Casa Romuli (or House of
Romulus, the legendary founder of Rome). Also here was the
Lupercal, reputedly where the twin boys (
Romulus and Remus) were suckled by a she-wolf and where the
Lupercalia festivities were held, as well as the
Roma quadrata. Finally, at its northwestern end, the region contained the still intact
Arch of Titus, the now ruined Baths of Elagabalus and the
Arch of Constantine, where it terminated. At the turn of the 5th century, the Regio contained 20
aediculae (shrines), 89
domūs (patrician houses), 48
horrea (warehouses), 44
balneae (bath houses) and 89
loci (fountains). ==Subdivisions==