Church of St. Polyeuctus

The Church of St. Polyeuctus (Greek: Ἅγιος Πολύευκτος, Hagios Polyeuktos) was an ancient Byzantine church in Constantinople (now Istanbul, Turkey) built by the noblewoman Anicia Juliana and dedicated to Saint Polyeuctus. Intended as an assertion of Juliana's own imperial lineage, it was a lavishly decorated building, and the largest church of the city before the construction of the Hagia Sophia. It introduced the large-scale use of Sassanid Persian decorative elements, and may have inaugurated the new architectural type of domed basilica, perfected in the later Hagia Sophia.

Little is known of the church's history after its construction. The building survived until the 11th century, after which it fell into decay, while several architectural elements were removed and reused in Constantinople and other cities. After being built over in the Ottoman period, the site of the church was rediscovered during excavations in the 1960s. The area, directly opposite the Istanbul Metropolitan Municipality City Hall, is now a preserved archaeological site open to visitors, although the sculptures have been removed to the Istanbul Archaeological Museum.

The church was commissioned by the noblewoman Anicia Juliana, descendant of several Western emperors, and was constructed between 524 and 527, during the reign of Justin I (r. 518–527). It was meant to replace an earlier church, built by Eudocia, wife of Theodosius II and Juliana's great-grandmother, to enshrine the relic skull of Saint Polyeuctus. The new church was thought to have been the largest in Constantinople before the building of the Hagia Sophia by Justin's nephew and heir, Justinian I (r. 527–565).

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