This is the monastery of Yuso, twin of Suso. Parts of the newer of the two (Yuso, pictured) date to the 11th century, while the older one (Suso) is built out of a cave and dates back to the 6th century. The monastery holds the impressive claims to the birthplace of modern written and spoken Spanish, as well as Basque. These appear both as written glosses to the Latin codex Aemilianensis 60. The monasteries are also famous for being the home of the thirteenth-century Castilian poet, Gonzalo de Berceo, author of the Milagros de Nuestra Señora, and the first Spanish poet to be known by name.
