I was in Lima recently, and there was a ruin right in the nice Miraflores area (with plenty of high-rises) that had been a temple complex of some sort. Where they hadn't excavated, the outer layer of brick had just crumbled to dirt, and looked like nothing special. Apparently part of the temple complex had been leveled and used as a soccer field as recently as the 1980s.
Even the structures built from stone were dismantled for the materials over the years. It's why Machu Picchu is such an amazing find--the locals didn't know about it and thus didn't tear it apart over the centuries. Compare this to grand sites like Saksaywaman that were picked apart down to the foundation by people looking for building material.
