Carretera A-1604 is a very exciting road in the province of Huesca, Aragon, Spain. The road is very scenic running along the Guarga River. It's very funny.
Located in the Sobrarbe comarca, in the heart of the Aragon Pyrenees, the drive is 50.8 km long. It’s paved in very bad conditions with potholes, and pretty narrow in parts. The road tops out at 1.295m (4,248ft) above the sea level. Road with little traffic. It’s used by motorcycle enthusiasts from around the world.
It runs west-east from the small town of Lanave (E7 road) towards Boltaña (N260 road). It’s also known as Carretera de la Guarguera. The last part of the road is pretty hairy, with some hairpin turns and very steep, with dangerous drop offs. Caravans are not recommended.