Writing guide-books to the antiquities of Rome has been going on for centuries and all those that have ever been written have steered a similar course, between fact and fiction, or rather, between two different kinds of reality. On the one hand, to a degree unmatched anywhere else in the world, Rome's physical past has continued to be woven into the fabric of its present, with buildings now well over 1,500, some well over 2,000 years old still standing (some even still functioning) as part of the modern city. Three thousand years of continuous occupation have produced one of the most deeply stratified and complex urban sites in existence. Up to 20 metres of deposits overlie the street levels of the C6 AD, which in their turn frequently represented a rise of about 2 metres compared with the imperial city of the C2 AD, and in places the C2 level is at least another 4 metres above that of the republican city--and so on back to the huts and cemeteries of the end of the Bronze Age. The sites appear in groups or in isolation, within designated 'archaeological zones' or on the side of a busy street, in a deep pit in the ground or in the middle of a traffic roundabout. Their survival has rarely had to do with their original purpose; that can only be said of the city walls, first laid out in AD 271-5, and continuously operative until breached for the last time by Garibaldi's forces on 20 September 1870. The other structures which have never been buried have usually survived by being converted (in varying states of decay) into churches, monasteries, fortresses, and palaces; some are massive concrete buildings, immune to natural elements and beyond most human means to destroy until the age of dynamite; later generations merely built into, around, or over them as if they were part of the bedrock. Some have been 'liberated' on various occasions from their later encumbrances; there was a rash of that during the French occupation of Rome in 1809-14 and again under the Fascist regime of 1921-44. In the late C19 concerted archaeological excavations were undertaken with the express purpose of rediscovering the Roman Forum, but they are the exception; practically every other site which has been dug up afresh came to light by chance in the course of redevelopment--and whether they have then been allowed to remain visible has been less a question of their archaeological importance, and more a question of their perceived historical significance.
For the second reality is that nowhere else is the archaeological record supplemented, at times overwhelmed, by quite so much historical evidence. Not only was Rome the stage for countless famous episodes (such as Horatio defending the Sublician bridge against the whole Etruscan army; Julius Caesar being murdered on the Ides of March in the curia of the porticus of Pompey and Mark Antony's speech in the forum . . .
