This is the mosque of Cerrah Paşa. Cerrah Mehmet Paşa was a barber and therefore a surgeon (cerrah), who performed the circumcision of the future Sultan Mehmet III. The latter appointed him Grand Vezir, as it turned out for only six months. The mosque dates from 1593 and was designed by Davut Ağa, Sinans successor as Chief Architect. (info: Strolling through Istanbul; Redhouse)