Lalibela is known for its distinctive rock-cut churches dating from the 12th and 13th centuries, which are pilgrimage sites for Coptic Christians. Carved out of rock, the subterranean monoliths include huge Bete Medhane Alem, and cross-shaped Bete Giyorgis. Many are joined by tunnels and trenches, and some have carved bas-reliefs and colored frescoes inside.