This text is a fragment of a guidebook to Istanbul: "Byzantine Secrets of Istanbul".

Similarly to the much better-known church of Constantinople -- Hagia Sophia -- also the present-day Hagia Eirene represents the last of many places of worship to be erected in the same location over many centuries. The well-preserved church, named after the Holy Peace, can now be found in the first courtyard of Istanbul's Topkapı Palace. Moreover, it is one of the few Eastern Roman churches in Constantinople that has never been converted into a mosque, and now functions as a museum and a concert hall.

Although there is no material evidence for this, according to the tradition, the first Christian church at this site was erected in the place of a pagan temple. The first Hagia Eirene was most likely built during a thorough reconstruction of the city, which turned a Greek trading colony into the new capital of the Roman Empire during the reign of Emperor Constantine I. Hagia Eirene began to serve the faithful at the end of the reign of this emperor, in 337. It was also the patriarchal cathedral before the first Hagia Sophia, built by Constantius II in 360, took over this role.

It was in the newly built Hagia Eirene that Paul I was elected as the Bishop of Constantinople in 337. He was an ardent opponent of the then popular Arianism, a Christian doctrine that rejected the dogma of the Holy Trinity. As a result of heated disputes between the supporters and the opponents of this doctrine, in which even Eastern and Western Roman emperors were involved, Paul I was placed three times on the episcopal throne of Constantinople and three times exiled from the capital. The riots between the supporters and the opponents of Bishop Paul I led to the panic and massacre of the faithful gathered in Hagia Eirene. Socrates Scholasticus, the author of the "History of the Church" covering the years 305–439, wrote that the crowd gathered in the church was chased away by the soldiers who murdered 3,150 people.

It is quite possible that it was in Hagia Eirene that the meetings of the First Council of Constantinople were held. It was convened in 381 by Emperor Theodosius I the Great in order to solve the theological problem of the pneumatomachian heresy, which denied the godhood of the Holy Ghost. As a result of the council's deliberations, the Niceno-Constantinopolitan Creed was created, roughly equivalent to the Nicene Creed with additional articles concerning the Holy Spirit and the church, the baptism, and the resurrection of the dead. Moreover, the council strengthened the position of Constantinople, as it was established that the bishop of Constantinople, and not Alexandria, was to have the primacy of honour following that of the bishop of Rome.

Hagia Eirene probably also served as the patriarchal cathedral in the early 5th century, after the fire that destroyed Hagia Sophia in 404. This fire broke out as a result of riots caused by the exile of the Bishop of Constantinople, John Chrysostom. This bishop, known as the Golden-mouthed, praised the principles of poverty, abstinence, and alms giving, and at the same time condemned the abuses of the imperial court. For this reason, he came into conflict with Empress Eudoxia, the wife of Emperor Arcadius, that led to his exile. John Chrysostom did not return alive to the imperial capital because he died of exhaustion during the journey. His relics were returned to Constantinople in 438, and they were initially kept in the Church of Hagia Eirene. Ultimately, however, they were placed in the Church of the Holy Apostles.

Both major churches of Constantinople -- Hagia Sophia and Hagia Eirene -- burned down during the riots of 532, known as the Nika revolt. Hagia Eirene was rebuilt by order of Emperor Justinian I, as the domed basilica, in 548. The reconstruction of Hagia Eirene was a part of Justinian's enormous plan to rebuild and expand Constantinople, in which over 30 churches were erected. Right next to Hagia Eirene, you can spot the ruins of what may have been the Samson Hospital, rebuilt during the same period. It was mentioned by Procopius of Caesarea, the most famous Byzantine historian, in his work "On Buildings":

"The church called after Eirene, which was next to the Great Church and had been burned down together with it, the Emperor Justinian rebuilt on a large scale, so that it was scarcely second to any of the churches in Byzantium, save that of Sophia. And between these two churches there was a certain hospice, devoted to those who were at once destitute and suffering from serious illness, those who were, namely, suffering in loss of both property and health. This was erected in early times by a certain pious man, Samson by name. And neither did this remain untouched by the rioters, but it caught fire together with the churches on either side of it and was destroyed. The Emperor Justinian rebuilt it, making it a nobler building in the beauty of its structure, and much larger in the number of its rooms. He has also endowed it with a generous annual income of money, to the end that through all time the ills of more sufferers may be cured."

In 564, a fire that destroyed many buildings in the area damaged the narthex and the atrium of Hagia Eirene. Another disaster hit the building in the 8th century, when the church was severely damaged by an earthquake, now dated by dendrochronology to the period after 753. The renovation of the building was ordered by Emperor Constantine V, who ruled in the years 741-775. At that time, the apse of Hagia Eirene was decorated with a simple mosaic depicting a cross because the emperor was a supporter of iconoclasm and opposed the veneration of images. By undertaking the renovation of the church, Emperor Constantine V wanted to be equalled to the most famous rulers of the empire -- Constantine the Great, Justinian and his wife Theodora, whose monograms adorn the capitals of the columns in the arcades of the building.

In 859, Hagia Eirene was the site of a local council which approved Photius I the Great to the episcopal throne of Constantinople, who assumed this office after the exile of Bishop Ignatius I from the city. It was the last significant event held at Hagia Eirene, recorded by chroniclers before the Ottoman conquest of Constantinople in 1453.

When Sultan Mehmed the Conqueror ordered the construction of Topkapı Palace in his new capital, Hagia Eirene was separated from Hagia Sophia by a wall surrounding the palace complex. The former church was located in the first courtyard of the palace, next to the Janissaries' quarters. They used the interior of the Hagia Eirene as a weapons warehouse known as İç Cebehane, the Inner Arsenal. With time, weapons and trophies captured by the Ottoman army during the conquests were also stored there. Late Ottoman art still visible in the dome of Hagia Eirene depicts weapons and musical instruments, reflecting this role of the building.

During the reign of Sultan Ahmed III, in the first half of the 18th century, Hagia Eirene functioned as an armoury -- Dar-ül Esliha -- the House of Arms. In the 19th century, its role changed thanks to Ahmed Fethi Pasha, then the marshal of the sultan's armoury. This politician travelled extensively throughout Europe and served as the ambassador of the Ottoman Empire to Russia, Austria, France, and Great Britain. Foreign experiences inspired him to create the first museum in the empire, and he chose Hagia Eirene as its seat. In 1846, he created a museum inside it, but as early as 1875 there was not enough space for more exhibits. The collection was then transferred to the Faïence Pavilion -- Çinili Köşk -- which was transformed into the Imperial Museum. Over time, this pavilion became part of the Istanbul Archaeological Museum.

Hagia Eirene then served as the Military Museum. There are photos that show the chain, which had been used to cut off access to the Golden Horn Bay, exhibited in the atrium of the church. The porphyry tombs of the Byzantine emperors were also stored at the same site, but most of them were moved to the Archaeological Museum. Currently, two of these sarcophagi can still be seen in the atrium of Hagia Eirene. In the 20th century, Hagia Eirene served as a concert hall for many years, and since 2014 it has been open to visitors as a museum.

A thorough understanding of the architecture of Hagia Eirene church is complicated because it was reconstructed and renovated several times. It is a building constructed mainly of bricks, on a rectangular plan with sides 32 and 57 meters long, not including the adjoining atrium. Most often, researchers assume that the lower parts of the building date back to the times of Justinian, i.e. to the 6th century, and the higher ones -- to the period of reconstruction of Constantine V after the earthquake in the 8th century. There are traces of several other buildings around the church, dating from the 6th to 8th centuries, including the Samson Hospital mentioned above. Moreover, in 1927, an L-shaped underground cistern, supported by 52 columns, was discovered on the southeast side of the church. This structure, dating back to the late antiquity, may have been part of the hospital's infrastructure.

Hagia Eirene from the Justinian period was a domed basilica. The dome, about 16 meters in diameter, was supported by pendentives erected over the elongated nave, with two aisles separated from the main nave by colonnades at the ground floor level. On the upper storey, the interior was surrounded on three sides by vaulted galleries. On the west side there was a narthex, and on the east -- an apse.

The redevelopment of Constantine V kept the basic plan and dimensions of Hagia Eirene, but also introduced some important changes. During the reconstruction, the original dome was raised and a second one, on an elliptical plan, was added. The foundations of the church were also strengthened and transverse barrel vaults were added to better support the dome. The reconstruction of the gallery's barrel vaults turned the church into a cross-domed basilica.

In the Ottoman times, the columns supporting the galleries were replaced with smaller ones. The appearance of the atrium was also changed, while a new gallery and a new main entrance were added. The marble slabs that once adorned the interior were used as the supports under the columns. Although Hagia Eirene was never transformed into a mosque, the cross at the top of its dome was replaced with the symbol of Islam -- a crescent moon.

The most characteristic preserved element of the Hagia Eirene decoration is the mosaic in the apse -- a rare example of sacral art from the iconoclasm period. Supporters of this movement replaced the depictions of people with symbols. Therefore, instead of the mosaic traditionally placed in the hemisphere above the apse, depicting Mary with the Child, i.e. Theotokos, Constantine V commissioned a decoration focused on the worship of the True Cross.

The mosaic shows a simple black cross standing on a three-tier podium and set against a golden background. The apse is surrounded by mosaics with floral and geometric patterns. Above the cross there are two inscriptions based on biblical psalms, partially recreated in the 19th century using paint to replace the missing pieces of the mosaic. These inscriptions praise the church as the House of God.

The three apse windows symbolize the Holy Trinity. Semicircular stairs in the apse, which served as a seat for clergymen -- the so-called synthronon -- is a symbol of Golgotha Hill, where Jesus was crucified. Interestingly, the Hagia Eirene synthronon is the only surviving solution of this type from Eastern Roman times preserved in Istanbul.

This text is a fragment of a guidebook to Istanbul: "Byzantine Secrets of Istanbul".