Arch of Theodosius
The Arch of Theodosius was a triple triumphal arch in the Forum of Theodosius. It is the only known monumental arch in Constantinople. It was completed by 393 when the forum itself was inaugurated and was part of a continuous effort in Late Antiquity Constantinople to rival Rome. It seems that the arch had statues of two sons of Theodosius, Arcadius and Honorius on each side with Theodosius in the center. It was likely destroyed by an earthquake.
Two marble based on of a monumental arch along with numerous pieces of architectural sculpture were discovered in Beyazıt in 1958. The main arch was originally around 7 meters wide and supported by four decorated columns standing on each base, was plausibly identified with one of two that straddled the Mese on either side of the Forum of Theodosius I. The columns of the arch have a similar design as those found in the Basilica Cistern.
Reconstruction by Naumann
Constantinople: Capital of Byzantium by Jonathan Harris
Brickstamps of Constantinople by Jonathan Bardill
Oxford Dictionary of Byzantium edited by Alexander P. Kazhdan
Arch of Theodosius (Byzantium 1200)
Columns and Monuments of Constantinople Photo Album (Byzantine Legacy Flickr)
Columns and Public Spaces (Nicholas V. Artamonoff Collection)