The Grutas de Mira de Aire, or Mira de Aire Caves, are a fascinating natural attraction located near the town of Mira de Aire, in the Leiria District of Portugal. These stunning limestone caves are one of the largest and most beautiful cave systems in Portugal, and they are renowned for their impressive rock formations, underground rivers, and breathtaking natural beauty.

The Mira de Aire Caves were formed over millions of years by the erosive action of water on the limestone rock, creating a labyrinth of underground passages, chambers, and caverns that extend for over 11 kilometers (about 7 miles). The caves are divided into several levels, with the main tour covering approximately 600 meters (about 1,970 feet) of accessible pathways that wind through the most spectacular sections of the cave system, including the Sala Grande (Big Hall), the Cúpula Vermelha (Red Dome), and the Lago das Canoas (Canoe Lake).

One of the highlights of the Grutas de Mira de Aire is the Sala Grande, a vast chamber with towering stalactites and stalagmites, some of which reach heights of over 30 meters (about 98 feet), creating a dramatic and awe-inspiring spectacle that showcases the incredible beauty and geological significance of the caves. The Cúpula Vermelha is another impressive feature of the cave system, with its striking red-colored dome and intricate rock formations that resemble cascading waterfalls, creating a surreal and otherworldly ambiance that captivates visitors and photographers alike.