The Valens Aqueduct is a Roman aqueduct which was the major water-providing system of the Eastern Roman capital of Constantinople.

Public Monuments

The architectural development of Constantinople may be divided into three main periods.

First Period (4th–early 7th C.)

Constantinople was built as a late antique city with all the normal features of contemporary urbanism, only more magnificent. A straight avenue bordered by colonnades (emboloi) was obligatory: at Constantinople this was the Mese, which ran from the arch of the Milion near the Hippodrome to the Capitolium, a distance of 1.7 km, then as far again to the Constantinian Golden Gate. This longitudinal avenue was crossed at right angles by another (later called emboloi tou Domninou), with a tetrapylon at the intersection. At intervals along the main avenue were squares, or forums (see Agora), each adorned with suitable monuments. Two of these were inherited from ancient Byzantion, namely the Strategion, later remodeled by Theodosios I, and the Tetrastoon, which became the Augustaion.

The umbilicus of Constantine's city consisted of a circular forum (called simply ho Phoros) bordered by porticoes. At its center stood a column (see Columns, Honorific) made of drums of porphyry and supporting a statue of the emperor wearing a radiate crown. The column is still preserved in a truncated form (Turk. Cemberlitaş). On the north side of the Phoros was the Senate House with a porch of porphyry columns; facing it on the south was a monumental fountain (nymphaeum). The next forum to the west (Forum Tauri, corresponding to modern Beyazit) was laid out by Theodosios I in imitation of Trajan's Forum in Rome: it had a triumphal arch on each side (parts of the west one are preserved; see Arch, monumental), a basilica and, on axis, a gigantic column covered with spiral reliefs commemorating the emperor's military exploits (destroyed ca.1500).

The next two forums to the west, the Forum Bovis (ho Bous) and the Amastrianos, are poorly documented. Then, on the city's seventh hill (Xerolophos), was the Forum of Arkadios, with a second spirally decorated column (pedestal preserved). At the western limit of the walled city, the Golden Gate (both Constantine's original and that constructed by Theodosios II farther west) had the form of a triumphal arch; evidence indicates that the processional way linking the two gates also received a monumental treatment.

Nearly every emperor from Constantine I to Phokas commemorated his reign by erecting monuments in the capital. Beyond those already mentioned, only two survive: the so-called Column of the Goths on the Seraglio Point, which may be Constantine's, and Marcian's Column. The colossal Corinthian capital discovered in 1959 in the courtyard of the Seraglio has been linked to a column of Leo I and the Barletta Colossus (U. Peschlow in Studien Deichmann 1:21–33). Justinian I was glorified by a column and equestrian statue in the Augustaion; Justin II erected a column of his own in the quarter called Deuteron and started to build another one (not completed) near the baths of Zeuxippos; Phokas put up a column near the Tetrapylon. In addition to imperial monuments, several statues of pagan gods, mythological figures, philosophers, and so on were imported from other cities by Constantine and his successors and placed in public baths, forums, the Hippodrome, and elsewhere. New honorific statues of persons other than emperors were also made, the last recorded one being a statue of Niketas, cousin of Herakleios (ca.614). A monumental weathervane called the Anemodoulion was decorated with bronze statues. These display monuments were put up for the city's adornment but also to express certain ideological messages (e.g., imperial victory, the wisdom of the senate, etc.) and to provide an appropriate setting for ceremonial occasions.

Public buildings of an ornate character included the two Senate Houses; the Basilike next to the Augustaion, which appears to have been a vast stoa with a gilded roof surrounding a central courtyard; the theaters (of which little is known); the Roman amphitheater (Kynegion) and the Hippodrome; the public baths, the biggest of which may have been the Constantianai (begun 345, completed 427) and which also included the Karosianai (built by Valens in 375), the Arkadianai (395), the Honorianai (412), the Helenianai, and the bath of Dagistheos (started by Anastasios I, completed by Justinian in 528) in addition to the famous baths of Zeuxippos and the ancient bath of Achilles near the Strategion. The construction of baths was a favored sector of imperial munificence because of the popularity of bathing.

Also constructed in the capital during the 4th through 6th C. were the Great Palace and the Hormisdas, Antiochos, and Lausos palaces. The principal churches erected in this period were St. Mary of Blachernai and St. Mary at Chalkoprateia, the Basilica of St. John at the Stoudios monastery, St. Polyeuktos, Hagia Sophia, St. Irene, Sts. Sergios and Bakchos, and the Holy Apostles.

Second Period (7th–12th C.)

The construction of display monuments ended in the early 7th C., by which time the city or, at any rate, its main avenues and squares must have resembled a vast stage set. The “dark age” that followed caused the abandonment of earlier urbanistic practices, the gradual ruination of public buildings, and a shift in popular mentality: the monuments that remained were no longer understood for what they were and assumed a mythic character. They were invested with occult power, either beneficent or maleficent, and interpreted as presages of things to come. The cryptic messages they conveyed could be decoded only by “philosophers.” It is in this manner that they are interpreted in the Patria of Constantinople.

The so-called Macedonian Renaissance brought a few instances of the collection and reuse of earlier pieces of sculpture and one recorded case of the restoration of a monument (the masonry obelisk of the Hippodrome by Constantine VII) but did not return to the monumental tradition of antiquity. The Macedonian and Komnenian dynasties, however, constituted a period of considerable construction activity, during which the Mangana and Blachernai palaces were built in Constantinople and the Bryas palace in the suburbs. New churches and monasteries of this time include the Nea Ekklesia, Myrelaion, Lips monastery, Kalenderhane Camii, and Pantokrator monastery.

Third Period (13th–15th C.)

Following the Fourth Crusade and the period of Latin occupation of Constantinople (1204–61), during which numerous buildings were damaged or fell into disrepair, a surge of new construction occurred under Michael VIII and Andronikos II. Perhaps to symbolize his work of restoration, Michael VIII erected a group of statuary near the Church of the Holy Apostles representing the emperor offering a model of the city to St. Michael. In addition to the palace of Tekfur Sarayi, several new monasteries and churches were built, most notably the South Church at the Lips monastery, Pammakaristos, Chora, and the Bebaias Elpidos nunnery.Cyril Mango

Kazhdan, Alexander, ed. The Oxford Dictionary of Byzantium. New York: Oxford University Press, 1991. oxfordreference

Cisterns

(κινστέρναι). Constantinople, with no rivers, few springs, and fast runoff of rainwater, needed reservoirs to tide the city over dry spells and lengthy sieges, when aqueducts might be threatened. Water from forests west of the city was introduced into open cisterns (total capacity approximately 900,000 cubic m [Janin, infra 202]) and more than 80 covered cisterns (capacity approximately 160,000 cubic m). Constantinople's daily consumption of water was about 10,000 cubic m. Most cisterns were built between the late 4th C. and early 7th C. as population burgeoned. The largest open cistern was that of Aetios (probably the eparch of the city in 419): built in 421, it measured 244 × 85 × about 14 m deep and had a capacity of between 250,000 and 300,000 cubic m. Covered cisterns included Binbirdirek (Philoxenos), whose superposed columns reached a height of 12.4 m and were set in 16 rows of 14 columns each (capacity about 40,000 cubic m), and the Basilike (Yerebatan Saray1), whose 336 columns, 8 m high and set in 12 rows of 28 each, supported a chamber capable of holding approximately 78,000 cubic m.

The major cisterns, usually placed on hills, supplied water to about 40 public baths as well as monasteries and churches. The use of columns rather than the brick and cement piers used by the Romans reduced maintenance costs; impost blocks make an early appearance in cisterns. Hydraulic cement (opus signinum) lined the structures.Katherine M. Kiefer, William Loerke

Kazhdan, Alexander, ed. The Oxford Dictionary of Byzantium. New York: Oxford University Press, 1991. oxfordreference