Originally named Hagia Theodosia for a woman martyred during a brief but violent period of Orthodox iconoclasm in the eight century, Rose Mosque, or Gul Camii, acquired it's new name after a tragic, though rather poetic, set of events.
On the eve of the final day of the Ottoman siege of Constantinople, legends holds that Emperor Constantine XI and the Orthodox Patriarch of the city held their final vigil here, praying for a miracle to deliver them from almost certain death. When the time came for the Emperor to lead his final defense, many hundreds of people remained in the church, adorning it with rose petals and chanting endless prayers for their safety.
The next day, the Ottomans broke through the walls and the city fell. When Sultan Mehmet's army reached Hagia Theodosia, they found it littered with rose petals and filled with heavy-hearted citizens. All who had remained were taken prisoner, and the church was converted for general military purposes.
Some two decades later, the Ottomans repaired the structure for use as a place of worship, calling it Rose Mosque in remembrance of its final days as a Christian church.