While the Dardanelles also separates Europe and Asia further south, the 19-mile Bosphorus uniquely cuts directly through the heart of Istanbul.

Two massive Medusa heads support columns in this ancient underground reservoir. They are positioned upside down and sideways, likely to negate her petrifying gaze.

The nickname comes from the 20,000 hand-painted blue ceramic tiles from Iznik that adorn the interior walls, as the mosque's exterior is actually grey stone.