There are older buildings in Istanbul and there are larger ones, but nothing else in the city holds attention quite like Hagia Sophia. Part of it is the age — fifteen centuries — and part is the light, which comes in through forty windows at the base of the dome and makes the whole ceiling look as though it is floating.
The building has been a cathedral, a mosque and a museum, and it is a mosque today. Nothing from those periods was erased, so Christian mosaics and Ottoman calligraphy share the same walls.
Entry is free; modest clothing is required and women should cover their heads. Visits pause for prayer. From Romance Istanbul Hotel it is a walk of about ten minutes, and the quietest time by far is the first hour after opening.