What is the importance of Topkapi Palace in the novel, The White Castle?

Topkapi Palace was the administrative, educational, and art center of the Empire for nearly four hundred years since Mehmed the Conqueror (1451 - 1481) until Sultan Abdulmecid (1839 - 1861). After the establishment of the Republic of Turkey, Topkapi Palace, was transformed into a museum on 1924 and it was also the first museum of the Republic of Turkey. The sultan lived in this palace and the characters visit him there.