At 3,355 m, Monte Perdido is the third-highest peak in the Pyrenees and the highest massif lying entirely within Spain. The standard ascent goes via the Góriz mountain refuge (reached in about four hours from the valley), with a high camp before the final push to the summit the next morning. The route is non-technical in summer but requires good fitness, mountain experience, and an eye on the weather — storms build fast on the massif.
The Góriz refuge is one of the busiest in the Pyrenees; book well ahead for summer nights. Even if you don't summit, the walk to Góriz is rewarding: the refuge sits in a high limestone plateau with views across the French border and down into the Ordesa canyon.
Note: The summit ascent involves steep snow and scree. Ice axes may be needed early in the season (June). Do not attempt without checking conditions.