Great cities are always changing, and as property developers and big businesses move in, often the first neighborhoods to lose their character are those that operate on the margins – places where economies are decidedly underground. Even though a lot of that gritty neighborhood character is lost to history, there are audioguides out there that capture the essence of times gone by.  Next time you're headed to New York, London, Tokyo, or Paris, plug in to one of these guides to experience a different, seamier side of city life.

Times Square, New York City
Perhaps the most obvious example of a once-gritty neighborhood that's lost its edge is New York's Times Square. To look at the chain restaurants, family-friendly stores, and hoards of tourists that clog the area today, there's no real sense of the adult theaters and sex shops that populated the streets from the 1960s to the 1990s. An audio walking tour ($1) from the Soundwalk company guides you through the streets and attempts to recreate those bygone days with the help of a narrator well-versed in its salubrious history.

Soho, London
London's Soho neighborhood hasn't quite met the same urban-Disneyland fate as Times Square, but it too has surrendered much of its past character to the march of the property developers. With Soundmap's audio walking tour (free), you can travel back to bohemian Soho, home to several generations of writers, artists, showgirls, gangsters, and philosophers. You will also hear from local characters including  self-proclaimed "rudest landlord in London," Norman Balon.

Kabukicho, Tokyo
Tokyo Realtime's Kabukicho tour ($5.99) takes listeners through a Tokyo district that is, for all its neon-bright facade, largely hidden to foreigners.  The tour features interviews with a bar owner and a rope bondage artist. It also provides insight into the carnival-like offerings of the area's thriving adult entertainment businesses – the strip joints, love hotels, and host bars. The tour also takes in more sedate locations such as movie theaters, restaurants, and billiard rooms. Soon after its release, the guide's author had to issue an update to remove several of the featured businesses that had been closed down by the then-governor's crusade to "Clean Up Tokyo" in preparation for its Olympic bid.

Pigalle, Paris
Narrated by singer/actress Lou Doillon (who also happens to be Jane Birkin's daughter), and featuring specially commissioned music by Sir Alice, Soundwalk's Pigalle tour ($1) comes with an "adults only" warning. The tour begins at the bohemian La Fourmi bar then continues off the beaten path through the back streets of Pigalle, taking in sex shops, dark alleys, nightclubs, and cabarets.