Locals from the valley of Karrantza thought they were being fooled. On 28 December 1957, the country’s own April Fool’s Day, a blowing-up in the Donoso Quarry opened a hole in the mountain, uncovering a secret, dazzling world that spread out into the bowels of the Armañón Nature Park. But the Pozalagua Cave is as real as the eccentric stalactites that crown the cavern and give it a magnificent feeling of unreality. It’s one of the most charming spots in the region and well beyond its boundaries.

The cave has the greatest concentration of eccentric stalactites in the world. These glittering structures sprout at whim and seem to defy gravity, intertwining in every direction with the strangest of shapes. They compose a unique setting, a surreal underground cathedral. Although discovered more than sixty years ago, those venturing inside Pozalagua still marvel at its magnificence. It is not a coincidence that the cave was chosen Repsol Guide’s Best Spot in 2013, an acknowledgement of the position it deserves among the country’s natural wonders.

The underground chamber makes for an impressive sight. The itinerary meanders through columns, flowstones and an almost dry lake above which thousands of eccentric stalactites grow lawlessly, depicting what seems to be an immense coral reef. The end of the gangway affords an unrivalled view of the cave and its grandeur, marked by bizarre structures and shapes. The temperature inside keeps stable at around 13 degrees Celsius all year round, which calls for warm clothes not only in winter.

Right opposite the cave, sculpted in a former dolomite quarry, there stands the Pozalagua auditorium, an outdoor stage with a capacity of 2,000 people. Concerts, operas and plays are frequently hosted here due to its perfect scale and acoustics.