Troy Day the Spaniards once they conquered the cities they stopped dstroying them. That’s why there are still ruins and temples of cities already empty when the Spaniards arrive. What they did in Mexico City was to take the stones from the Aztec buildings to build Spanish buildings but even then there are still Aztec ruins in the heart of Mexico City, with the most important temple besides the catholic cathedral and other ruins around in other parts of the city, even one subway station has an old pyramid. The ones that were interested in the destruction of códex and idols were the catholic priests, not the soldiers nor the conquistadores and not all of them because even some codex writers were catholic priests and wrote the believes and ways of life of the Aztecs to preserve them for the future, this is how we know about them and what they believed.