Fenâri Îsâ Mosque was made of two former Eastern Orthodox churches. In 908, the Byzantine admiral Constantine Lips inaugurated a nunnery on the site. The church was built on the remains of another shrine from the 6th century, and used the tombstones of an ancient Roman cemetery. Relics of Saint Irene were stored here.
After the Latin invasion and the restoration of the Byzantine Empire, between 1286 and 1304, Empress Theodora, widow of Emperor Michael VIII Palaiologos (r. 1259–1282), erected another church dedicated to St. John the Baptist south of the first church.
In 1497–1498, shortly after the Fall of Constantinople, the south church was converted into a mescit (a small mosque). The edifice burned down in 1633, was restored in 1636 by Grand Vizier Bayram Pasha, who upgraded the building to cami ('mosque') and converted the north church into a tekke (a dervish lodge). The building burned once more in 1918, and was abandoned. During excavations performed in 1929, twenty-two sarcophagi have been found. The complex has been thoroughly restored between the 1950s and 1960s by the Byzantine Institute of America, and since then serves again as a mosque.
As a whole, this complex represents a notable example of middle and late Byzantine Architecture in Istanbul.
References:Rosenborg Palace was built in the period 1606-34 as Christian IV’s summerhouse just outside the ramparts of Copenhagen. Christian IV was very fond of the palace and often stayed at the castle when he resided in Copenhagen, and it was here that he died in 1648. After his death, the palace passed to his son King Frederik III, who together with his queen, Sophie Amalie, carried out several types of modernisation.
The last king who used the place as a residence was Frederik IV, and around 1720, Rosenborg was abandoned in favor of Frederiksborg Palace.Through the 1700s, considerable art treasures were collected at Rosenborg Castle, among other things items from the estates of deceased royalty and from Christiansborg after the fire there in 1794.
Soon the idea of a museum arose, and that was realised in 1833, which is The Royal Danish Collection’s official year of establishment.