Lucerne, Switzerland: Museggmauer

City walls were popular several hundred years ago in Europe. Most countries weren't fully developed yet, and you never knew who might show up and invade your territory. So ... call in the builders.

Lucerne was no different. It built a good-sized wall during the 1200s. That includes the Chapel Bridge; you can notice the tower in the middle of the river. But that wasn't quite good enough. Between 1370 and 1420, the Musegg Wall went up. Happily, most of it is still up. Nine of the 10 towers remain; the 10th and part of the wall and a gate were dismantled in 1860.

Here's the fun part: You can still walk along the wall, at least partly. Some of the towers are even open to the public, although the stairs are a little sleep and small folks will have an easier time getting around. The walkway isn't particularly narrow, and it's not a place for fun and games either. Still, if you can handle a little effort, the views of the city are excellent.