Advertisement

The Caves of Altamira

Anthropologists went wild when they discovered these charcoal paintings. Not only are they pretty good, but one painting dates back 35,000 years. It's remarkable it survived to tell us so much about people back then. Today, though, the art has been degraded. No one did it intentionally, we are happy to report. But human breath smogging up the caves interacted with the paint on the wall. The colors started to change!

Wikimedia Commons / Rameessos

Because of the potential for damage, the caves were closed to the public shortly thereafter.  Since 2002, you can't go in. All you can do is look at a nearby replica. But it's not the same!