The Church of Holy Wisdom, which used to be the cathedral of the city in Byzantine times, stands at the junction of Ayia Sofia and Ermou Streets. It is dedicated to Christ, the true Word and Wisdom of God, and celebrated on 14 September, the day of the Elevation of the Precious Cross.
The oldest written reference to Ayia Sofia dates back to 795, but archeological data show that it was built at some time around the end of the 7th century, on the site of an Early Christian, five-aisled basilica of the 5th century. It would appear that this church was destroyed by an earthquake in ca. 620. In texts of the 10th, 11th, 12th and 13th centuries, it is referred to as the "Great Church", "the central church of the metropolis" and "the metropolis". At the time of Latin occupation of Thessaloniki (1204-1224), the church became the cathedral of the Latins, but even after the restoration of Byzantine rule in the city, it continued to serve as the seat of the bishop, until 1523/24.

The church is a typical example of a transitional cruciform church with a dome and peristyle, a development of the new architectural style, the domed basilica, which was first introduced in Ayia Sofia in Constantinople. Typically this is an almost square ground-plan, in the centre of which four massive pillars and four arches supporting an immense arch on a four-sided drum describe the shape of a cross. Alternate pillars and columns respectively separate the central space from the two side aisles which, together with the narthex, form the peristyle. On the eastern side, the tripartite sanctuary is attached to the four-side nucleus as an independent architectural feature. Covering for the perimeter space is provided by barrel vaults. Initially, there was a gallery only above the side aisles, but after the renovation of the church in the 11th century (probably after the earthquake in 1037) it was extended to over the narthex, too. At this time the lighting of the west facade of the church was installed with ten single-lobed windows and the outer narthex added. The unified wooden roof of the church also dates back to the renovation phase of the 11th century. The brickwork follows Constantinopolitan models, since, in the older parts there are alternate bands of hewn limestone and bricks set in reddish mortar.

The mosaic decoration of the church is the product of three different phases. From the three mosaic monograms of the emperor Konstantinos VI, his mother, Irene the Athenian, and Theofilos, Bishop of Thessaloniki, the non-pictorial decoration of the arch in the sanctuary, with crosses and leaves in successive squares, can be dated to about 780-788, i.e. to the time of the iconoclast struggle. It appears that the great cross in the apse, the shadow of which can be discerned below the form of the Mother of God, also belonged to this phase. In the dome, the majestic composition of the Ascension belongs to the end of the 9th century and is a prime example of the so-called "Renaissance of the period of the Macedonian emperors". The inscription on the base of the dome, which mentions the name of Archbishop Paul of Thessaloniki (880-885), is not related to the composition of the mosaic. In the apse of the sanctuary, there is a depiction of the Mother of God Holding the Child, enthroned, a work probably dating to the 11th or 12th century, and it is this which covers the great iconoclastic cross.

The wall-paintings of the church date back to the 11th century and are related to the construction of the narthex, after 1037. A few depictions of monastic saints have survived in the arches of the windows; among them saint Theodora of Thessaloniki.

The sculpture in the church is not the product of a single phase. On the columns of the ground floor and on their capitals, material from the 5th and 6th centuries was used. The pulpit, a product of the 5th century, was taken to Constantinople in 1905. The marble cornices seem to be from the same time as the construction of the church.

The church was the burial place of outstanding Church leaders, such as Gregory Palamas, Metropolitan of Thessaloniki, whose tomb was here until the church was turned into a mosque. Besides, the monumental tomb, complete with wall-paintings from the 12th century, which was found here and is now on show at the Museum of Byzantine Culture, has been attributed to an archbishop of Thessaloniki.

After the imposition of Ottoman power, the church continued to function as the Orthodox cathedral until 1523/24, when it was turned into a mosque at the time of Maktul Ibrahim Pasha. At the north-west corner, a tower was built for entry to the galleries, and this was probably the mosque's first minaret. In 1890, the building was damaged by fire and then restored by the Byzantinist Charles Diehl in 1907-1909. On 29 June 1913, the church was re-sanctified and handed over for Christian worship. After the earthquakes of 1978, restoration and stabilization work was undertaken in relation to the superstructure and the mosaic decorations, while excavation work was carried out at the same time in the interior of the church and its surrounding area.

Church of Saint Sophia (Hagia Sofia)
Church of Saint Sophia (Hagia Sofia)
Church of Saint Sophia (Hagia Sofia)
Church of Saint Sophia (Hagia Sofia)
Church of Saint Sophia (Hagia Sofia)