one bane of ancient ruins was, weirdly enough, railroads. Apparently, these consumed quite a few old buildings as they were scavenged for railroad ballast. Harrapa, Tiahuanaco, several places in the middle east.
So what if Cortez, in 1521, decides to not tear down the step pyramid of Templo Mayor, but leave the pyramid and approach stairs intact and build a Christian church on top of the pyramid, in place of the Aztec temples? Would the later Spanish governors and bishops review that decision?
Agreed. But for the aforementioned political reasons, I can't see the Aztec Empire surviving the conquest. The Tarascans might be able too, though I'm not as informed about them: However, Tzintzuntzan has largely survived to the present day relatively intact.There was a small Christian shrine put on the very top of Tenochtitlan's Pyramid after Cortes and the conquistadors destroyed all the religious idols. It was later razed down with the rest of the pyramid and replaced with a small church which would later be replaced with the modern day Cathedral. It's not going to happen so long as the Spanish are in charge.