The "Longest Roman Aqueduct"

Introduction
Despite the attribution of the Bozdoðan Kemeri to the emperor Valens (AD 364-78) construction work probably dates from AD 345, in the reign of Constantius II (Mango 1995). Very little work had been carried out on the Thracian aqueducts until a recent publication by the hydrological engineer Professor Kâzim Çeçen, whose investigation of the long-distance system demonstrated the enormity of the construction (Çeçen 1996a; see also important earlier studies by Oreshkov 1915, 88-103; Dirimtekin 1959, 1968). Çeçen also produced the first map, showing in outline, the course of the water supply line based on interpolation from topographical maps and the fragmentary remains he observed.

From its furthest source to its ultimate destination, the water supply line travels through the catchment areas of four major rivers in Thrace: the Ergene, the Istranca (Binkilic) Dere, the Karamandere and the Alibey. Building on Çeçen's work we have been able to redefine the aqueduct, not as a single long line, but as a vast and complex dendritic system, i.e. drawing in water from multiple sources in Thrace, rather than merely from a single major spring. The principal and furthest source was located at springs just west of the small town of Vize (Bizye) near the village of Pazarlý. During its period of greatest extent however the long-distance channel also collected water from other sources en route, most notably those in the Karamandere and Ergene valleys and also probably from a major spring near the village of Pinarca. Additional minor tributaries to the system have also been observed in the vicinity of the Anastasian Wall.

Closer to the city the situation becomes much more complicated as supply lines converge from the various sources to the west and north. One of the major complications in addressing issues of chronology, sources and destinations is caused by the fact that several different spring sources have been exploited throughout the history of the city and the early lines were often rebuilt and renovated. The Valens Aqueduct itself carried a number of channels dating, it seems, from various different periods (Dalman 1933). The closer sources in the Forest of Belgrade and at Halkalý were the most enduring and were individually exploited by the Roman, Byzantine and the Ottoman city. The substantial redevelopment of these lines after the 15th century has however meant that it is hard to unravel the earlier material from the Ottoman (Çeçen 1996b).

Most of our fieldwork has been focused on the water system in the vicinity of Anastasian Wall where the existence of two substanial parallel channels has been discovered, separated by over 6m in altitude near Kurþunlugerme, but gradually converging further east. The low-level channel is generally 2.4m high and 1.6m wide. The high-level channel is a narrower guage, at 0.60m wide with a height of 1m.