As far as landmarks go however, I gotta go with the Great Pyramids of Egypt.
Here's an excerpt from a thing I was working on for a different wiki:
"One of the first to master the element of Earth was King Djoser, founder of the Third Dynasty and the pharaoh behind the Step Pyramid at Saqqara, which is believed to be the oldest large-scale monumental stone structure in not only Egypt, but the entire world. The pyramid stands in the middle of a funerary complex, which was the first architectural project to have been built entirely out of stone.
The social implications of such a large and carefully sculpted stone structure existing are staggering. The process of building such a structure would have been far more labor-intensive than previous monuments of mud-brick. This suggests that Djoser’s government had a new level of control over resources, both material and human, than had ever been seen before."
Despite being so ancient, these structures have withstood the test of time and inspired people from many generations with their magnitude and wonder. I'll finish off with this arabic proverb:
"Man fears Time, Time fears Pyramids and Sphinxes."