Which mountain range forms the border between France and Spain?

The Pyrenees form the mountain border between France and Spain. This range runs across southwestern Europe, separating the Iberian Peninsula from the rest of continental Europe, while the small country of Andorra lies within the mountain system between the two larger states.

The range extends for nearly 500 kilometers from the Bay of Biscay to the Mediterranean coast. Its highest summit is Aneto, which rises to 3,404 meters in the Spanish Pyrenees. The main crest generally follows the political divide, although the international boundary does not match the watershed perfectly everywhere.

A common mix-up is confusing the Pyrenees with the Alps. The Alps are farther east and include famous peaks such as Mont Blanc and the Matterhorn; the Pyrenees are the range associated with the France–Spain border. The border was formally defined through treaties developed after the 1659 Treaty of the Pyrenees.