The origin of this building, which lies on the southern slope of the seventh hill of
Constantinople and overlooks the
Sea of Marmara, is not certain. Traditional accounts state that in the year 325
Helena, the mother of
Constantine I, coming back from
Jerusalem with the
True Cross and entering the City through the Port
tou Psomatheou, left in this place some vases ("Gastria") containing aromatic herbs collected on
Calvary. She subsequently founded a nunnery at the site. In reality, no monastery was established in Constantinople before the last quarter of the fourth century, so this has to be considered only a legend. At that time
Theoktiste, mother of Empress
Theodora (wife of Emperor
Theophilos and
restorer of the cult of the
icons) bought in the quarter of
Psamathia a house from the Patrician Niketas (possibly
Saint Nicetas the Patrician), and established there a nunnery. The title of
Ktētorissa (foundress), together with the property of the buildings, was inherited by her daughter Theodora. Together with her daughters
Thekla, Anna, Anastasia and Pulcheria, Theodora was removed to the monastery by her brother
Bardas after her deposition as regent for her son,
Michael III, in 856. All of them were forced to accept the
tonsure, although her eldest daughter, Thekla, was eventually recalled by Michael to serve as a mistress for his favourite,
Basil the Macedonian. The 10th-century emperor
Constantine VII Porphyrogennetos writes in his book
De Ceremoniis that the church of the nunnery served also as a
mausoleum for the members of Theodora's family. The Empress, her brother
Petronas, her mother and her three daughters were all buried there. The last mention of Gastria before 1453 comes from a Russian pilgrim, who visited the City during the second quarter of the fifteenth century. He remembers a nunnery placed near the
Golden Gate, where the
relics of
Saint Euphemia and
Saint Eudokia were
venerated. This building could well be identified with Gastria. Shortly after the
Fall of Constantinople, Hayrettin
Effendi,
Sancaktar (standard-bearer) of
Sultan Mehmed II, converted the building into a
mescit (oratory) and was buried there. The charter for this
religious foundation has not survived. The
1894 Istanbul earthquake, which had its epicentre under the Sea of Marmara, partially destroyed the mosque, which was restored only between 1973 and 1976. ==Description==