Babylon 66

As much as I like Route 66, I don't think we can compare the cultural value of the ruins along it to those left by 7,000 years of (four major) civilizations in what is now Iraq, even if we assume the viewpoint of a 36^th century archaeologist. A list of 100 sites worldwide by a US group, the "World Monuments Fund's 2008 watch list" included Route 66 and Iraq among the most endangered sites worldwide, according to this AFP news story.