Ankgor Wat in 2000 still had signs of Khmer Rouge and the deadly genocide so many people in our generation have never learned about. They were still clearing land mines when I took a boat up the Tol Sap River to wander these incredible temple grounds. The architects of this city predated London and were craftsmen beyond any modern compare. If you go today, the scene is far more civilized but still worth the travel.
It's important to remember the people who learned what we think we are the first to discover came far before we can imagine.