Grutas dos Alvados is a system of underground caves located in the Serra d'Aire e Candeeiros Natural Park in central Portugal. The caves feature impressive rock formations, underground lakes, and unique geological features. Visitors can take a guided tour of the caves, which lasts about an hour and covers approximately 500 meters of underground passages. One of the highlights of the tour is the "Catedral" chamber, which features a 20-meter-high ceiling and beautiful rock formations. A visit to Grutas dos Alvados is a must-see for nature lovers, adventure seekers, and anyone looking for a unique experience.