On the slope of the fourth hill at the northern end of Constantinople, east of the now lost Church of the Holy Apostles, rises the large monastic complex of Christ Pantokrator. Its construction is attributed to the emperor John II Komnenos (1118-1143) and his wife Irene of Hungary (1118-1143), according to the typikon of the monastery, written in 1136 by the emperor himself, which survives till today.
From this monumental complex, which functioned as a charitable institution with a nursing home and a hospital, three temples and some annexes on the southern side, which are connected to the residency of the emperor, are what remains in place today. The south church, the katholikon (principal church) of the monks’ monastery dedicated to Christ Pantokrator, is the biggest cross-in-square preserved in the capital and one of the largest in the whole Byzantine world. Its magnificence was completed with excellent mosaics, known to us only through historical sources, and with the opus sectile pavement, which decorated the central floor of the church. The north church was dedicated to Virgin Eleousa (Merciful, since it was related to the adjacent charitable institution), and everyone was allowed to enter, in contradiction to the south church, where an abaton, a ban for women pilgrims, was implemented.
The two churches are connected on the west by a continuous narthex, which has a second floor. In a later phase, on the south part, which corresponded to the katholikon of the monastery, an outer narthex was built. The space between the two cross-in-square churches was filled with a domed chapel of Archangel Michael, which served as the mausoleum of the Komnenoi and also of a few members of the Palaiologoi dynasty, among them the emperor Manuel II (1391-1425) and his family.
After the Fall of Constantinople to the Crusaders in 1204, the complex passed to the hands of the Venetians till 1261, when it was restored to the authority of the Orthodox Church. After the Fall of Constantinople to the Ottomans in 1453, it functioned as a Muslim religious-educational institution (medrese) and then as a mosque called Molla Zeyrek Camii, in honor of the first hoca (religious teacher) Zeyrek Molla Efendi. The name is preserved till today, frequently expanded to Zeyrek Kilise (ekklesia/church) Camii, a reference made to the initial function of the complex.
Many restoration works have repeatedly taken place in the complex. The first ones, from 1953 till 1967, included the cleaning of the western and southern side, while in the decade of 1990 the monument was part of a restoration program in cooperation with the University of Illinois. The last restoration works lasted from 2010 till very recently.