Not exactly Regency, but with the Olympic Games going on and the cool Olympic Rings displayed on London Bridge, I thought it interesting that in 1831 the new London Bridge opened. The current London Bridge isn't that one, of course; in 1831 who knew automobile traffic would be such that they'd have to tear the bridge down and start again?
The 1831 bridge is currently in Lake Havasu City, which I've actually visited solely because they have the London Bridge! I can't find one single picture, I suspect they're either on my old laptop or (heaven forbid!) they've been taken with film and are in a shoebox...someplace.
John Rennie deisgned this bridge, and work began in 1824 about 100 feet from the then current (and 600 years old) bridge.