Temples, shrines, gardens, the Imperial Palace . . . Why, tourist guidebooks are full of places that echo the form and spirit of the Old Edo that once was. But they're only telling you a part of the story.

This city of an estimated 1 million souls -- which, back in the 17th century, made it the world's most populous -- was a beehive of human activity, not all of it legal. The Tokugawa rulers took a stern, legalistic approach to violators of the law, and punishment, when it came, was unforgiving, swift and often public.

If you've grown tired of mundane cultural sites, or seek a more down-to-earth view of how people lived, played and died in Old Edo, these gloomy remnants of its dark side await your visit. All you have to do is hop onto the Eidan Hibiya subway line: They can all be accessed easily from stations along the way.