Every traveler loves walking a city's streets and checking out cool shops and restaurants. If you're only seeing what's above ground, however, you're merely scraping the surface. Tours in many cities bring visitors deep below street level for a glimpse of secret hideouts, spy tunnels, and catacombs.
Underground tours are commonly found in cities with storied histories. In Rome, you can view dungeons, medieval mosaics, and ruins under churches and prisons. Join a tour in paris and you'll be strolling through tunnels dating back to the 1200s.
Some of the most interesting tours explore areas created during wartimes. You can walk through underground bunkers in Vienna that served as World War II air-raid shelters. Outside Seoul, Korea, there's a tunnel that was carved years ago in secret by the North Koreans.
Underground tours are also offered in a few U.S. cities. A 90-minute tour in Seattle visits three blocks that were covered up and built over after the great fire in 1889.
On another tour, in Portland, Oregon, you'll learn how transient laborers and sailors in the nineteenth century were kidnapped, brought underground, and later sold as slaves. We're pretty sure folks in the Pacific Northwest are more friendly these days.