Hagia Sophia
Now a museum, Hagia Sophia was first built as a basilica in the 6th century and later converted into a mosque by the Ottomans. Under its massive dome, more than 18 storeys high, visitors may view galleries of beautiful mosaics from the Byzantine era.
Naval Museum
Founded in 1897, the Naval Museum showcases the maritime might of the Ottomans. Besides exhibits on celebrated Turkish sailors, the museum features an enormous collection of historical artifacts, including a 17th-century warship.