Dealul Melcului Geological Reserve is one of the most fascinating protected natural areas in Harghita County, located near the village of Corund. Famous for its unique aragonite, travertine, and calcite formations, the reserve showcases a rare geological phenomenon created by mineral-rich spring waters depositing calcium carbonate over thousands of years. Visitors can follow an educational trail featuring active mineral springs, rocky outcrops, and unusual geological formations in a peaceful natural setting.