Tower Bridge ★☆☆
This faux-medieval bridge is well worth the photo stop—but you might not bother with the exhibition
The fancifully Victorian Tower Bridge are as much a London icon as Big Ben's clock tower, a suspension bascule bridge (drawbridge) supported by turreted twin towers in a medieval style only the late 19C could dream up (it was built 1886–94).
The pair of elevated walkways tying the two towers together aren't just there to offer a lovely viewpoint for visitors—including a glass-bottomed section so you can watch the cars below whizz by 42 meters (138 feet) beneath your feet. They help disperse the horizontal forces exerted on the towers by the suspension sections of the landward sections of the bridge.
Getting that view means paying for the Tower Bridge Experience, which is actually not really worth the time. I mean, yes, you get the views, but are also subjected to the interactive displays—manned by Victorian-garbed mannequins—showcasing the old coal-driven steam engines, machines, and massive counterweights that, until the 1970s, raised and lowered the roadway below. (Now it's all done by hydraulics and computers.) It's marginally interesting, but also cheesy and overblown.
Dead Man's Hole
Fun aside: Under the east side of the northern end of the Tower Bridge is Dead Man's Hole, a former mortuary where bodies—washed to this spot by the tidal action of the Thames—were fished from the waters and laid out for identification.
Tips
Well, I prefer just taking a few pictures of it from the Tower of London and moving on.
The little museum—grandly called the Tower Bridge Experience—takes about 30–45 minutes, though, again, I would just skip it. There are far more interesting bits of London to get to.