For a long time we were pretty sure that we had the oldest free-standing structures (i.e. buildings) in the world:

https://en.wikipedia.org/wiki/Megalithic_Temples_of_Malta

Apparently there's an even older contender in Turkey now, but, anyway you slice it, this stuff is old. The most recent of them (2500 BC) roughly equate in age to the oldest pyramids of Egypt.