You're an experienced climber looking for a challenge? Steep-sided and bare, the 8,200 feet of the Naranjo de Bulnes beckon. Rearing up from the Picos de Europa in northwest Spain like a cracked molar sorely in need of a divine dentist, it's called "the orange one" because of its rich sunset color. Choose from around 70 different ascents. Easiest—or, rather, least difficult—and most popular is the Hermanos Martinez route, two hours of tough climbing up the southern face. The most demanding routes (strictly for the specialist) thread for almost 2,000 feet up the near-vertical western face. At its feet, the Refugio Vega de Urriellu mountain hut, a friendly house of Babel, draws climbers from around the world.