The city was seated on a craggy rock, which hung over the sea, and communicated by a steep and narrow path with the land.

Since the approach was difficult, the attack might be deemed impossible: the Persian conqueror had strengthened the fortifications of Justinian; and the places least inaccessible were covered by additional bulwarks.
In this important fortress, the vigilance of Chosroes had deposited a magazine of offensive and defensive arms, sufficient for five times the number, not only of the garrison, but of the besiegers themselves.

The stock of flour and salt provisions was adequate to the consumption of five years; the want of wine was supplied by vinegar; and of grain from whence a strong liquor was extracted, and a triple aqueduct eluded the diligence, and even the suspicions, of the enemy.

But the firmest defence of Petra was placed in the valor of fifteen hundred Persians, who resisted the assaults of the Romans, whilst, in a softer vein of earth, a mine was secretly perforated.

The wall, supported by slender and temporary props, hung tottering in the air; but Dagisteus delayed the attack till he had secured a specific recompense; and the town was relieved before the return of his messenger from Constantinople.