Tour the ruins of an abandoned elevated freight railroad in central Philadelphia.
The company itself may be evil but, cartographically speaking, Google is revolutionary. They first stood out from the competition when they enabled users to drag the map instead of clicking on arrows. Then they made satellite photos easily accessible. Suddenly everyone was looking at shots of their home, their place of work, their favorite park. An enthusiast of urban geography, I find that aerial shots carry a wealth of hidden data. For example, in most cities, you can correlate a neighborhood's density of trees to personal wealth. Before venturing to the South Bronx for the first time, I was able to make a quick mental note of where the area's infamous housing projects were by searching the satellite photos for the unusual saw-tooth shaped buildings that cast large shadows on their low-rise neighbors.
Recently, in certain cities, they've added a "street view" function where you can actually look at 360-degree panoramic photos of any coordinate in town. While still in Portland, I was able to map my future bike commute in New York and view the route at street level from afar, looking for dangerous intersections and studying the quality of pavement in the bike lane.
Allowing users to customize their own maps has brought a lot of personality to an otherwise excessively dorky endeavor. Of course people mapped the obvious stuff: traffic congestion, earthquakes. Esoteric maps emerged as well, like rising sea levels, proposed but never built highways, and, my personal favorite, field recordings from forests and cities all around the world.
"Urban explorers," who examine otherwise forbidden parts of civilization, find the damndest things. Many have photographed various asylums and jails in the many uninhabited islands around New York. The rust belt, Detroit in particular, is a haven for urban explorers breaking into everything from factories to office towers. In 1994, a group of explorers claimed to have found the Spetzmetro, a secret subway system under Moscow connecting the government centers to a far flung rural town (presumably so officials could escape in the event of a rebellion). They don't restrict themselves to abandoned sites either: you're just as likely to find them scaling the cables of a suspension bridge or kayaking down storm sewers.
Despite my fascination, I've actually taken up such an adventure only a handful of times. The most successful was during a trip to Philadelphia in '05 when Kayt and I found an entrance to the Reading Viaduct, a long abandoned freight railroad beautifully overgrown with whatever it is that thrives in Philly's smoggy humid climate. This is a unique find because, unlike a forested factory in the middle of nowhere, the viaduct is located in a very central location. And yet few seem aware of its existence.
New York's very similar High Line, in Chelsea, is set to be the next big public park and adjacent real estate has already responded. If you walk down 10th Av you're likely to see construction crews removing vegetation and installing benches. In Philadelphia, on the other hand, the Reading Viaduct is sitting tight.
