Just beyond the Arch of Titus lies the Clivus Palatinus, which rises up a slight incline to the heights of the Colle Palatino (Palatine Hill), the oldest inhabited site in Rome. Despite its location overlooking the Forum's traffic and attendant noise, the Palatine was the most coveted address for ancient Rome's rich and famous. More than a few of the Twelve Caesars called the Palatine home, including Caligula, who was murdered in the still-standing and unnerving (even today) tunnel, the Cryptoporticus. The palace of Tiberius was the first to be built here; others followed, notably the gigantic extravaganza constructed for Emperor Domitian. But perhaps the most famous lodging goes back to Rome's very beginning. Once upon a time, early skeptics termed Romulus a solar myth. About a century ago, however, Rome's greatest archaeologist, Rodolfo Lanciani, excavated a site on the hill and uncovered the remains of an Iron Age settlement dating back to the 9th century BC, supporting the belief that Romulus, founder of Rome, lived here. The story goes that the twins Romulus and Remus were abandoned as infants but were suckled by a she wolf on the banks of the Tiber and adopted by a shepherd. Encouraged by the gods to build a city, the twins chose a site in 735 BC, fortifying it with a wall that Lanciani identified by digging on the Palatine. During the building of the city, the brothers quarreled, and, in a fit of anger, Romulus killed Remus.

During the Republican era the hill was an important religious center, housing the Temple of Cybele and the Temple of Victory, as well as an exclusive residential area for wealthy families. Hortensius, Cicero, Catiline, Crassus, and Agrippa all had homes here. Augustus was born on the hill, and as he rose in power he bought up surrounding estates and transformed them into private libraries, halls, and a temple to the god Apollo; the House of Livia, reserved for Augustus's wife, is the best preserved structure. Her son by a previous marriage, Emperor Tiberius, was one of the first to build a palace here, and other emperors followed suit. The structures most visible today date back to the late 1st century AD, when the Palatine experienced an extensive remodeling under Emperor Domitian. His architects put up two separate palaces, called Domus Augustana and Domus Flavia, as well as a stadium. The palaces were enlarged again under Septimius Severus in the early 2nd century AD. The lack of undeveloped space forced his workers to reshape the hill, razing old structures, filling in hollows, and building terraces. During the Renaissance, the powerful Farnese family built gardens atop the ruins overlooking the Forum. Known as the Orti Farnesiani, they were Europe's first botanical gardens, and were partly destroyed during 19th-century excavations. The hill has undergone extensive restorations, with a layout that allows visitors to appreciate the hill in its entirety -- from the Iron Age to the Renaissance pleasure gardens.