Quito, the capital city, is located in a high mountain valley on the foothills of the Pichincha (volcano). The town of Baños de Agua Santa features hot springs swimming pools on the foothills of the Tungurahua in the Central Cordillera. The road from Baños to Puyo has long been known for its narrowness, curves and sheer drops (only one lane in some places, on one area, actually cut into the side of a cliff so that the cliff roofs over it). The most important east-west road across the Andes is the road from Quito to Lago Agrio, which is paved for most of its length yet is heavily traveled by tractor-trailers—and the Trans-Ecuadorian Oil Pipeline serves as the guardrail for long stretches of this road.