The two animals were meant to reflect the prestige of this vast Persian empire, which fell in 330 B.C. when Alexander the Great sacked and burned Persepolis and its opulent palaces. The lion and the bull have been fighting, locked in stone, for nearly 2,500 years-ever since an ancient sculptor carved them into a slab of black limestone and set them into a monumental staircase at Persepolis, the royal center of the great Achaemenid Empire.