The Grutas de Mira de Aire are a stunning series of limestone caves located in the municipality of Mira de Aire, Portugal. Discovered in 1947, these caves are known for their impressive stalactites and stalagmites, formed over thousands of years. The caves extend for about 11 kilometers, with only a portion open to the public for guided tours. Visitors can explore the enchanting underground chambers, which feature unique rock formations and underground lakes. The caves are part of the larger Natural Park of Serras de Aire e Candeeiros, making them a popular destination for nature lovers and tourists interested in geology and natural history.