A massive citadel built atop a 150-foot-tall hill of solid rock looms over Aleppo's old quarter. Fortresses have risen above this northern Syrian city since Roman times. But at the heart of the citadel, amid ruins of Ottoman palaces and hidden behind high walls that date to the Crusader era, a team of German and Syrian archaeologists is clearing debris from a large pit that shows this hilltop was significant long before the Romans arrived. Here, amid clouds of dust, a battered basalt sphinx and a lion—both standing seven feet tall—guard the entrance to one of the great religious centers of ancient times, the sanctuary of the storm god Adda.