Lalibela's reason for existence is its rock-hewn churches — eleven structures carved downward into the volcanic rock of the Lasta mountains in the 12th and 13th centuries. They are divided into two main groups connected by tunnels and trenches, with a third outlier, Biete Giorgis, standing alone to the southwest. The complex is a UNESCO World Heritage Site and one of the great architectural achievements of the medieval world. Beyond the churches, Lalibela rewards those who explore on foot — the surrounding hills offer views over the town and access to remote shrines, and the Saturday market draws traders from across the region.