Baalbek (; / ALA-LC: Ba‘albak) is a town in the Beqaa Valley of Lebanon situated east of the Litani River. It is famous for its exquisitely detailed yet monumentally scaled temple ruins of the Roman period, when Baalbek, then known as Heliopolis, was one of the largest sanctuaries in the empire. It is Lebanon's greatest Roman treasure, and it can be counted among the wonders of the ancient world, containing some of the largest and best preserved Roman ruins.