In 1962, attempts to clean up a landfill by burning it set fire to the coal mine underneath Centralia, Pennsylvania. The fire has been going strong ever since. Most of Centralia is in ruins and its population has dropped from over 1,000 residents in 1981 to less than 10 in 2007. As the area is loaded with rich deposits of coal, the spreading underground fire is expected to threaten the neighboring town of Ashland in the near future. There are no immediate plans to extinguish the fire, which is consuming an eight-mile seam containing enough coal to fuel it for upwards of 250 years.
So you want to visit Centralia PA ...
Centralia Pennsylvania (many photos)
Centralia, Pennsylvania wiki
hat tip to wtf_nature