That bridge/aqueduct is crazy -- built in 40-60 AD with no mortar! Lots of background in the Wikipedia entry including photos of key features. To think that I've always been impressed by a comparatively tiny aqueduct in my hometown that was built in 1838. The Pont du Gard was constructed approx. 1,800 years earlier!
To quote Spinal Tap:
"It really puts perspective on things, doesn't it?"
"Too much. Too much f**king perspective!"