One of the hot spots in the novel is the Tokatlian Hotel. Built in 1897, it was destroyed by fire in 1954. It is held to be one of the most admired hotels of its time, and Agatha Christie also penned Hercule Poirot checking in to the Tokatlian Hotel in "Murder on the Orient Express".
The Tokatlian Hotel in Constantinople was one of the places where the main character met his secret contacts.