The History Channel is running a ten-part series called Life After People. The program examines what the world will look like once all human life has been wiped out. The corresponding website has many features including some disturbing photo galleries. Here's a few examples:
The Houston Astrodome; about 20 years after the human race disappears. It's eroding and will succumb around the 100-year mark.
Chicago's Wrigley Field; about 25 years after the human race disappears. The shrubbery has completely taken over the stadium. Hopefully, the Cubs win the World Series at least once before the end of human existence. (Found this photo on Big League Stew)
Part of Chicago's train system; about 50 years after the human race disappears. This reminds me of the skyline in Wall-E.
These photos are just from the first two episodes. I'm very interested to see what episodes 3-10 will yield.