One of the most biologically diverse and ecologically significant landmarks in America, the Potomac Gorge, near Washington, D.C., has held an important place in human history since the Ice Age. Naturalist and author Melanie Choukas-Bradley leads a virtual journey along the most dramatic section of the 405-mile-long river: the 15-mile stretch in which it originates at Great Falls in Maryland and Virginia and flows, often through dramatic cliffs and bluffs, to Theodore Roosevelt Island in the District.