a manuscript or piece of writing material on which later writing has been superimposed on effaced earlier writing.
-something reused or altered but still bearing visible traces of its earlier form.
(Shorter Oxford Dictionary, OUP)

Rome is so interesting because it is made up of the constant layering of century upon century. This is not an original comment, it’s not called the Eternal City for nothing, but this merging of history can be a little frustrating; the city becomes a soup of centuries in which it is tricky to distinguish one period from another. Humans like taxonomical order, labelling things helps us feel that we understand them, but sometimes one has to surrender to the hodge-podge in all its eclectic glory. My favourite reference to this palimpsest was made by Sigmund Freud in the introduction to “Civilisation and its Discontents”:

“…let us make the fantastic supposition that Rome were not a human dwelling-place, but a mental entity with just as long and varied a past history: that is, in which nothing once constructed had perished, and all the earlier stages of development had survived alongside the latest. This would mean that in Rome the palaces of the Caesars were still standing on the Palatine and the Septizonium of Septimius Severus was still towering to its old height; that the beautiful statues were still standing in the colonnade of the Castle of St. Angelo, as they were up to its siege by the Goths, and so on. But more still: where the Palazzo Caffarelli stands there would also be, without this being removed, the Temple of Jupiter Capitolinus, not merely in its latest form, moreover, as the Romans of the Caesars saw it, but also in its earliest shape, when it still wore an Etruscan design and was adorned with terra-cotta antifixae. Where the Coliseum stands now, we could at the same time admire Nero’s Golden House; on the Piazza of the Pantheon we should find out only the Pantheon of today as bequeathed to us by Hadrian, but on the same site also Agrippa’s original edifice; indeed, the same ground would support the church of Santa Maria sopra Minerva and the old temple over which it was built. And the observer would need merely to shift the focus of his eyes, perhaps, or change his position, in order to call up a view of either the one or the other.”