This is the Yeni Valide Camii, built between 1708-1710 by Ahmet III and dedicated to his mother the Valide Rabia Gülnüş Ümmettullah. Her türbe (grave monument) is in a kind of aviary that you can see to the left. In front you see a "very attractive wooden façade, a later addition, which is the entrance to the imperial loge. And: the mosque itself is in the classical style at its very last gaps and before the baroque influence had come to liven it up."(Strolling through Istanbul; Redhouse).