The area of the Palatine is about 25 acres with a maximum height of 51 m above sea level. It is the central hill of the seven hills of Rome joined at one time with the Esquiline and the Velia. It was the first hill area to become a settlement. Much of the Palatine has not been excavated, except for the area nearest the Tiber. The residence of Augustus (and Tiberius, and Domitian), the Temple of Apollo and temples of Victory and the Great Mother (Magan Mater) are there. The exact location on the Palatine of Romulus' home and the Lupercal grotto at the foot of the hill are unknown. Legend from an even earlier period locates Evander and his son Pallas' band of Arcadian Greeks on this hill. Iron age huts and possibly earlier tombs have been excavated.
Update: BBC News' 'Mythical Roman cave' unearthed reported, on November 20, 2007, that Italian archaeologists think they've found the Lupercal cave, near the palace of Augustus, 16m (52ft) underground. The dimensions of the circular structure are: 8m (26ft) high and 7.5m (24ft) in diameter.
Reference: Rome and Environs, by Filippo Coarelli.