Istanbul’s 400-year old Sultan Ahmed Mosque, otherwise known as the Blue Mosque for its blue-tiled interior, is one of only two mosques in Turkey that has six minarets. Before the public address system was introduced, muezzin, or prayer-callers, would climb the narrow spiral staircases five times a day to announce the call to prayer. But when Charles Annenberg Weingarten tries to replicate their ascent, he has an unexpected encounter in the dark stairway.