The Palace pf the Prophyrohnitus ( Tekfur Sarayı ) is located in Fatih district of Istanbul. It is closed to city walls between Edirnekapı - Ayvansaray. It is the only surviving part of the Palace of Blachernae; therefore ,this three storey palace has an important place in art history. it became the main residence of the Byzantine emperors at around the 12 th century. During Ottoman Period it was put to diverse and curious uses such as glass manufacture and even as a pen for royal giraffes.
Google Maps - Tekfur Palace

The Palace of the Porphyrogenitus ( Tekfur ) is closed to Caria Museum. How to go Caria Museum? Or you follow from Edirnekapı to Ayvansaray next to city wall.