Grand Loop Road is Yellowstone National Park’s main road network, a roughly 140-mile circuit in northwestern Wyoming that connects many of the park’s most famous features, including Mammoth Hot Springs, major geyser basins, the Grand Canyon of the Yellowstone, Tower Fall, and Yellowstone Lake. Planned largely in Yellowstone’s early military-administration years by Captain Hiram M. Chittenden of the U.S. Army Corps of Engineers, the route later received its present name in 1923 from Harry W. Frantz. Beyond serving as a scenic drive, it is a historic district and a central part of Yellowstone’s built landscape, linking major developed areas and adjoining other historic districts across the park.