The Gazi Iskender Pasha Mosque dates from 1559-60, the founder was vezir who was governor of Bosnia. Strolling through Istanbul says “It is of the simplest type, has a wooden porch and roof with a flat ceiling, but both porch and roof are clearly later, indeed modern.” Formerly there seems to have been a dome inside, which is now absent. The founders türbe is nearby.

Inside a man was reciting the Koran all by himself. He told me he went through that book several times a year.

Note there is another Iskender mosque in Fatih, this one is in Kanlica, a village on the Asian side of the Bosporus beyond the second bridge.