Hagia Sophia (Sophia Cathedral) was built in the 11th century in the center of Kyiv by order of Yaroslav the Wise. At the turn of the 17th-18th centuries, it was externally rebuilt in the Ukrainian baroque style. Inside the Cathedral, many ancient frescoes and mosaics have been preserved, including the famous Oranta. Sophia Cathedral became the first architectural monument on the territory of Ukraine included in the UNESCO World Heritage List (in 1990).

Sophia Cathedral is a five-nave, five-apse cross-domed temple with 13 domes. From three sides it is surrounded by two-tiered galleries. It is made of plinths - wide, thin bricks. The length of the cathedral without galleries is 29.5 m, width - 29.3; with galleries: 41.7 and 54.6. The height to the top of the main dome is 28.6 m, the size of the dome square is 7.6 m.
It was built by Constantinople builders with the participation of Kiev masters. Meanwhile, it is impossible to find direct analogues of St. Sophia Cathedral in the Byzantine architecture of that time. The temples that were then built in the empire were usually smaller, had only 3 naves and one dome. It is assumed that the Byzantines were given the task of creating a large temple for solemn ceremonies, the main temple of Russia, which they solved by increasing the number of naves and adding dome drums to illuminate them.

The interior of the cathedral has preserved a large number of frescoes and mosaics from the 11th century. In the central dome there is a mosaic depicting Christ, on the sides of it are the archangels. Of these, only one is an ancient mosaic, the rest have not survived and were completed in the 19th century by M. A. Vrubel with oil paints. The figures of the apostles are depicted on the drum, below, on the sails of the dome, there are evangelists. Among them, only the Apostle Paul and the Evangelist Mark have survived from ancient times. The most famous mosaic of the cathedral is the Virgin "Indestructible Wall", located in the conch (vaulted part) of the altar apse. The palette of mosaics has 177 shades.
The galleries of the cathedral are decorated with frescoes, the upper galleries depict the daughters (southern wall) and sons (northern) of Yaroslav the Wise. On the western wall, dismantled at the end of the 17th century, there were images of Yaroslav himself with a model of the cathedral in his hand and his wife Irina. The walls and vaults of the stair towers bear secular frescoes depicting scenes from the life of Byzantine emperors. Also on the walls of the temple, many graffiti have been preserved, including those from the 11th-12th centuries.

About 100 graves were located in the cathedral, as well as on its territory. The graves of Yaroslav the Wise and his wife Irina have been preserved. The rest, including Vladimir Monomakh, were lost.

Different chronicles call the date of laying the cathedral in 1017 or 1037. Given the political situation in Russia, the second date seems more likely. Initially, the cathedral was not plastered: in order to be able to imagine its original appearance, sections of open masonry were left on the facades.
In 1240, the St. Sophia Cathedral was plundered and destroyed by the warriors of Batu, in 1385-90. Metropolitan Cyprian, recreated it from the ruins, after which it was in desolation for more than three and a half centuries, although it continued to operate. In 1596, the cathedral passed to the Ukrainian Greek Catholic (Uniate) Church, in the 1630s it was taken from it by the Kiev Metropolitan Peter Mohyla, who restored the cathedral and founded a monastery under it. Work on the renovation of the temple continued until 1740, when it finally acquired its current appearance.

Hetman Mazepa made a significant contribution to the preservation and restoration of the cathedral. He built the bell tower of St. Sophia Cathedral. To this day, the bell, cast by order of the hetman, has been preserved, which is located on the second floor of the bell tower. The bell bears the name "Mazepa".

In 1934, the architectural complex, which, in addition to the St. Sophia Cathedral, includes a bell tower, the metropolitan's house, a bursa, a refectory, a southern entrance tower, a western gate, a fraternal building, cells and a consistory, was declared the Sophia Museum State Architectural and Historical Reserve.