Cuevas de Nerja is a 4.8-kilometre limestone cave system in the village of Maro on Spain's Costa del Sol, four kilometres east of Nerja town and 56 kilometres east of Málaga. Carved out of the karstic mountain over more than five million years by groundwater dissolving the limestone, the cave's interior is a sequence of vast galleries — some chambers reach 30 metres high and 100 metres across — filled with stalactites, stalagmites, and limestone columns. The largest of these, the central column of the Cataclysm Hall, rises 32 metres in a single fused column and is the largest natural stalagmite ever measured.
The cave was lost to human memory until 12 January 1959, when five teenage boys from Maro went bat-hunting and found a narrow opening — La Mina — behind some bushes; they squeezed in and discovered the chambers within. Excavations since have produced human remains, ceramics, and a series of red-pigment paintings on the cave walls. Some of the seal paintings have been radiocarbon-dated by some specialists to roughly 42,000 years before present, which would place them among the earliest known cave art in Europe. The dating remains debated by specialists in palaeolithic art, and Cuevas de Nerja is recognised on UNESCO's tentative list of World Heritage candidates.
Today the cave is operated by Fundación Cueva de Nerja, a non-profit foundation that handles conservation, scientific research, and visitor access. Five of the chambers are open to the public on a self-guided one-hour route; the rest of the system, including the upper galleries where the most fragile paintings sit, is closed to all but accredited researchers. Every July and August the Hall of the Cascade — a chamber with extraordinary natural acoustics — hosts the International Festival of Music and Dance of Nerja, one of Spain's longest-running classical festivals.