Charles and Josette Lenars/Corbis

The imposing 75-foot-high, 225-foot-long Temple of Bacchus looms over the ruined city of Baalbek in eastern Lebanon. Once a Phoenician religious center devoted to the Semitic god Baal, Baalbek was conquered by the Seleucid Greeks in the fourth century B.C.E. and renamed Heliopolis (City of the Sun). Three centuries later, it was absorbed into the Roman Empire. The emperor Augustus so admired the ancient city—and its strategic location—that in 16 B.C.E. he founded a new Roman colony and military outpost there. Over the next 300 years, his successors would transform Heliopolis into a showcase of Roman colonial architecture, filling it with some of the largest and most lavishly ornamented religious sanctuaries in the classical world.