Calar Alto is a high mountain pass at an elevation of 2.168m (7,113ft) above the sea level, located in the Sierra de Los Filabres, a mountain range in Andalusia, Spain. The pass is traversed by the AL871 road. On the top of the mountain there’s an astronomical observatory. It's one of the highest mountain roads of Spain.
The surface of the road is asphalted. This road is usually open all year, but it can be closed anytime when the access is not cleared of snow. The summit hosts the Calar Alto astronomical observatory.
There are 2 possible routes to reach the summit. Starting from Aulago, the ascent is 29.7 km long. Over this distance, the elevation gain is 1.377 meters. The average percentage is 4.6 %. The max. slope is 10% just after Aulago. And starting from Gérgal, the ascent is 22.8 km long. Over this distance, the elevation gain is 1.390 meters. The average percentage is 6.1 %.