The Dumbarton Bridge, built in 1914-1915 to take Q Street NW over Rock Creek Park. The bridge is curved because Q Street isn't aligned between Georgetown and Dupont Circle. Four buffalo stand at either end of the bridge: http://www.pbase.com/helenpb/image/92597174
I have always seen this wonderful old bridge from the car on the parkway, but yesterday we parked and went in search of it on foot. Unfortunately, it simply wasn't possible to get a shot I liked of the entire structure from close up, but I love the detail (which I hadn't known existed).