Located in the Greenwood-Afton Rural Historic District, the Blue Ridge Tunnel (also commonly known as the Crozet Tunnel) is a single-track railroad tunnel constructed between 1850 and 1857 that was opened for use in 1858.  It is located 500 feet below the Rockfish Gap and straddles the county line between Nelson and Augusta counties. The gap was historically and remains a well-used area to cross the Blue Ridge Mountains between the Piedmont and Shenandoah Valley. Carved from greenstone, the tunnel was designed and its construction was overseen by engineer Claudius Crozet. Crozet, the best known Chief Engineer of Virginia, contributed to the formation of the curriculum at the United States Military Academy and the creation of the Virginia Military Institute. The tunnel was constructed by a labor force of primarily Irish immigrant labor, supplemented for a short time with hired-out enslaved African Americans. The Blue Ridge Tunnel remains the longest tunnel that was hand-dug using black powder blasting, and dug without the use of ventilation shafts. In 1944, the Blue Ridge Tunnel was replaced with a larger tunnel that runs parallel to the original. The tunnel was recognized by the American Society of Civil Engineers as a National Historic Civil Engineering Landmark in 1976. Today, it is the centerpiece of a 2.25 mile recreational hiking and biking trail.