Mangana (Μάγγανα “Arsenal”) was situated on the eastern side of the acropolis along the Propontis maritime walls. It had several important building there, including the Monastery of St. George, the Monastery of Christ Philanthropos and the Palace of Mangana. As it is now in a military zone of Topkapı Palace, it is not open to the public.  
The area was developed during the reign of Emperor Constantine IX Monomachos (1042-1055), third husband of Empress Zoe. He established the Monastery of St. George, a hospital and a law school there. In addition, he also built a palace and constructed lavish gardens around the monastery nearby. The Monastery of St. George quickly became one of the most important monasteries in the capital. It was included in imperial processions on April 23 when the feast of St. George was celebrated. It later had an extensive library and housed numerous important relics, including the relics of Christ’s passion. A Russian pilgrim records that the monastery had all the Savior's Passion relics: the purple robe, the blood, the spear, the reed, the sponge, and part of Christ’s beard. The monastery continued to function until 1453, when dervishes began to use it. 
Later the Monastery of Christ Philanthropos was founded by Eirene Choumnaina, the wife of despotes John Palaiologos, son of Andronikos II Palaiologos. It was a double monastery, with a male monastery and a convent. The convent, which housed 100 nuns and an unknown number of monks, was one of the largest in 14th-century Constantinople. The monastery, frequented by pilgrims, was noted for a miraculous appearance of Christ and as resting place of St. Aberkios. Its hagiasma continued to be visited by Orthodox Christian, especially for the feast of the Transfiguration of Christ, until the 19th century despite the fact that it lay within the walls of Topkapı Palace. 
After the construction of of Topkapı Palace, it seems that the remaining Byzantine structures were razed and only the substructures survived. In 1871 eastern sections of the Palace of Mangana and Monastery of St. George were destroyed during the construction of the railway.
During the occupation of Istanbul, the French army camping at Topkapı excavated the region in 1922-1923, bringing to light the ruins of several structures in the Mangana quarter, which were identified as the churches of St. George, Theotokos Hodegon and Christ Philanthropos, along with the Palace of Mangana. There was not enough time to excavate the entire region, though the results were later published by Demangel and Mamboury. The identification of Christ Philanthropos is often considered untenable, while the other identifications are commonly accepted. There are several cisterns located in this area, including one under the palace and two connected to the Monastery of St. George.