Random question:

The Pyramids were once covered with beautiful polished marble. Since then, they have been the victim of vandals and others looking for construction material. Many other ancient monuments have experienced significant damage as a result of both natural events (earthquakes, etc.) and human greed.

In principle, we could repair these monuments. Ignoring, for the moment, the costs of doing so, would it be better to restore them to the state they were in when they were built, or leave them as they are?