Istanbul formerly known as Byzantium and Constantinople, is the most populous city in Turkey. Founded under the name of Byzantion (Βυζάντιον) on the Sarayburnu promontory around 660 BCE, it was reestablished as Constantinople in 330 CE, Ottomans conquered the city in 1453 CE and transformed it into an Islamic stronghold and the seat of the Ottoman Caliphate.
Located at the confluence of the Bosphorus and the Black Sea, to the north of Joshua's Hill, in Istanbul, it is the last Byzantine castle standing in Turkey. Yoros also known as the Genoese Castle, it was intermittently occupied throughout the course of the Byzantine Empire. It was first conquered by Ottoman forces in 1305, but retaken by the Byzantines shortly thereafter. Bayezid I took the castle again in 1391 while preparing for his siege of Constantinople.
The Süleymaniye Mosque or better known as the mosque of Suleyman the Magnificent, was built in the 16th century by the great Ottoman architect Mimar Sinan for Sultan Suleyman the Magnificient, also known as the Legislator. It stands on a hilltop (3rd hill) dominating the Golden Horn and contributing to the skyline of Istanbul. The mosque is the largest mosque of Istanbul.
The mosque was commissioned by Suleiman the Magnificent and designed by the imperial architect Mimar Sinan and forms part of the Süleymaniye Külliyesi (Suleimanye Complex). The complex is laid out on an irregular plot of land conforming to the topography of the site, which was terraced and uneven.