In southwestern Pennsylvania, the 4,541-foot-long (1,384-meter) tunnel that runs underneath Laurel Ridge has had many uses since it was first carved out in the late 19th century.

Originally the structure had been built for a planned South Pennsylvania Railroad, but after that project fell through, the structure was incorporated into a new high-speed roadway, the Pennsylvania Turnpike. When it first opened in 1940, the turnpike was hailed as the newest, fastest way to travel across the state.

But the single-tube Laurel Hill Tunnel, along with several other tunnels along the route, proved to be a traffic bottleneck. In 1964, a new leg of road diverted the road around the tunnel, and soon after it fell into disrepair. The abandoned piece of infrastructure was used for things like material storage, a shooting range (or so says one reference), and likely many other fun things that folks can do in abandoned tunnels. 

After sitting empty for several decades, the Laurel Hill Tunnel found a new purpose in 2004. It has been cleared of debris, enclosed, and turned into a mile-long, climate-controlled testing facility used by Chip Ganassi Racing for testing racecars. According to Racecar Engineering, the tunnel’s railroad roots make it well-suited for testing cars at speeds up to—and perhaps over—100 miles per hour.

The original concrete surround to the tunnel opening is visible, and deteriorating, but now a metal tube protrudes out from it, ending in large garage doors. You can’t see in, but the whole setup is an interesting and ingenious-looking mashup, even from the outside.