Palace of Antiochos

In the 7th century, a part of the palace was converted into the church–more properly a martyrion, a martyr's shrine–of St Euphemia in the Hippodrome (Ἀγία Εὐφημία ἐν τῷ Ἱπποδρομίῳ, Hagia Euphēmia en tō Hippodromiō), which survived until the Palaiologan period.

As a cubicularius (chamberlain), he was tutor to the young emperor and eventually rose to the post of praepositus sacri cubiculi and the rank of patricius.

[10] According to tradition, the bones of the saint were ordered thrown into the sea by Emperor Leo III the Isaurian (ruled 717–741) or by his son, Constantine V (r. 741–775).

[11] The church survived until the end of the Byzantine Empire, being redecorated in the late 13th century with frescoes in the Palaiologan style.

The southern one, inaccessible to the public today, featured the large apsed hexagonal hall which was later converted into the Church of Saint Euphemia, connected to a wide semicircular portico, some 60 m in diameter and enclosing a courtyard paved with marble.

[4] The northern section, located between the street that ran along the western wall of the Hippodrome and the Mese thoroughfare, was until recently misidentified as the Palace of Lausus.

[4] In the 5th century, when the palace was imperial property, an elongated hallway was added to the rotunda in the west, accessed through a double-apsed vestibule.

[12] The excavations uncovered the remains of the synthronon (seats for the clergy, a cathedra), the altar foundation, the chancel barrier, and a solea (an elevated podium).

[12] A series of frescoes, dating to the late 13th century, survive on the southwestern wall of the church, and can be seen behind a protective glass.