I already wrote about this Marian shrine in the mountains as the Lourdes of Spain.
The history goes back to around 800 A.D. when the local king, Pelayo, defeated the "Moors." Well, either he defeated them or they were routed by the Blessed Virgin, but Asturias remained the only part of Spain never under Moorish domination. Here at Covadonga, Mary gets all the credit for that.
The early shrine is located right in the mountain cave where Pelayo encountered Our Lady. Pilgrims access it through a series of walkways (lined with signs reminding visitors to maintain silence and NOT to take pictures--a request I reluctantly complied with while within the sacred domains, but not once I got back outside!).
A century or two ago, a full-sized Basilica was built on the next hilltop, and more recently a pilgrim hostel and retreat center. The logo itself tells the story of Covadonga, if you know how to read the heraldry.