Formed over millions of years by the action of rainwater on the limestone, The Gruta de Mira de Aire complex of underground caves is a stunning experience. Discovered in 1947 and elected “Natural Wonder” of Portugal in 2010, it is the biggest cave complex in Portugal. Located around 1h15 min drive north of Lisbon, today one can safely visit part of the caves that altogether consists of 11 km underground. By a set of stairways one descends into the underground complex and can start to appreciate it´s beautiful and unique formations, underground galleries, “lakes” and “rivers”, all well organized and beautifully lit up.
The mountain region of Serra de Aire and Candeeiros, where the caves are located, is characterized by not being crossed by any river, as rainwater seeps almost completely into the crevices of the calcareous rock rather than running down the slopes and into rivers. Unlike other rocks, limestone is dissolved by water and unique formations are created by nature, such as stalactites (formations growing from the ceiling) and stalagmites (formations growing from the ground).
In 1947, the first men to enter the cave threw thick ropes and descended to a small gallery. Advancing they found themselves as if in an open window over a cliff. A few days later, they came back with more ropes and went down to the first room where their immensity barely showed the walls and stalactites that hung from the ceiling. Today the visit is much more comfortable and done in a safe and professional way.
In the end of the visit there is a small museum with some interesting geological artefacts and the complex offers also a cafeteria and restaurant. Before you leave the area don´t forget to get a glimpse of the “plain” between the mountains, under which the caves are located.
