Istanbul's first mosque designed in Baroque style, Nuruosmaniye Mosque, was built by architect mustafa Ağa and a non-Muslim Greek master Simeon Kalfa on one of the seven hills of Istanbul. It is located right next to the entrance of the Grand Bazaar in the Çemberlitas neighborhood of Fatih district. The construction of the mosque started in 1748 on the request of Sultan Mahmud, but on his death it was completed by the support of his brother and successor Sultan Osman III in 1755. The mosque was named “Nuruosmaniye”, meaning “the light of Osman”, after Osman III, but also because the mosque has many windows providing lots of light in the mosque. Nuruosmaniye Mosque was built as a part of a larger complex that consisted of a madrasa (Islamic school), imaret (soup kitchen), muvakkit's (timekeeper's) chamber, library, han (trade centre) and surrounding shops. In 2010, the restoration work on the mosque commenced. The mosque was re-opened for worship in 2012.
The mosque was constructed during an era of increased Western influence in architecture, and as such, Nuruosmaniye Mosque can be considered a milestone of ottoman Architecture. It also has some distinctive architectural characteristics distinguishing it from other mosques. First, it is the first royal religious complex that displays baroque and neo-classical elements such as shells, scrolls, molded cornices, and cartouches in its flamboyant surface decoration. Second, it has a porched-shaped polygonal courtyard without an ablution fountain, which is a common feature in ottoman architecture. Another important feature of the building is the polygonal shape of the mihrab (niche) projection and the way it is covered with a half dome. The mosque has one of the biggest domes amongst Ottoman structures, with 32 windows surrounding it. The mosque is also illuminated by 174 windows, and has two minarets with two balconies.