"It was at Rome, on the 15th of October 1764,as I sat musing amid the ruins of the capitol, while the bare-footed friars were singing vespers in the temple of Jupiter, that the idea of writing the decline and fall of the city first started to my mind.... But my original plan was circumscribed to the decay of the City, rather than of the Empire"
That's Edward Gibbon, of course. Her is talking about the basilica (Greek word, Roman temple) of St. Mary of the Altar of Heaven, once the Temple of Jupiter Moneta, the site (so it is said) where the Tibertine Sybil foresaw the coming of Christ.
I'm a sucker for these cross-cultural references. I suppose in a sense you could say that any European cathedral in Europe is a shadow of its classical ancestor, but a particular favorite is the cathedral at Syracuse in Sicily, fleshed out in the Seventh Century around the Doric columns of its Greek ancestor, then refitted at the beginning of the 18th (after an earthquake) with an assertive Baroque facade. I remember lounging on a bench outside the north wall one night, watching the Sicilians make their passeggiata while a band played "New York, New York."
Now here is another, new to me: the "Cathedral" (still in business) tucked into the middle of the Great Mosque at Córdoba in Spain. Evidently it began life around 600 AD as a Christian church under the Visigoths, then refashioned in its Islamic role in 784, and re-Chrisitanized when Ferdinand III chased the Moors off to Grenada in1236. And its history may not have ended: in 2010 a couple security guards were injured, reputedly when they tried to stop a couple of young Muslims from praying in the contended site. That picture above is just a cellphone snap and the lower part is in shadows but what you are looking at is (a) a recycled Roman column (with Corinthian capital) topped in turn by (b) a Visigothic arch; (c) a Romanesque Arch; (d) a Baroque spandrel; and (e) a dome. The inevitable reference is to Yeats' "Lapis Lazuli:"
On their own feet they came, or on shipboard,
Camelback, horseback, ass-back, mule-back,
Old civilizations put to the sword.