Imagine being able to take a train to Great Falls. That was once reality.
Today, the Washington & Old Dominion (W&OD) is a paved bicycle trail used for fun and for commuting across Northern Virginia. Of course, the Washington & Old Dominion was originally a railroad — one with a long and convoluted history that helped form communities along it including Dunn Loring, Reston, Herndon, Sterling, and Ashburn.
Source: ggwash.org