The “Official Istanbul Site” HowtoIstanbul has the following information: The Merkez Efendi Mosque was built on the site of a dervish lodge which had been commissioned by Süleyman the Great and built by the architect Sinan in 1517. After the death of Merkez Efendi, the mosque that bears his name was built in his memory between 1552-1572.
According to another story, the mosque’s construction began in 1580 and it opened to worshipers in 1582. Restored during the reign of Mahmud II, the mosque still bears many of the features of the original.
Merkez Efendi was famous for his strength as well as for inventing mesir paste and having served as a doctor. Süleyman the Great frequently visited his tomb which is located in the mosque’s courtyard. Next to the tomb is a çilehane built in keeping with the beliefs and traditions of Merkez Efendi’s sect. Merkez Efendi was said to gone here to isolate himself from the world.
Built on a rectangular plan, the mosque is made of stone. Its door and windows were made from round brick arches The tomb of Merkez Efendi and his family, a public fountain, a cistern to supply water to the mosque, and the çilehane are all found in the mosque’s wide courtyard.