摘要: Description　　The Bridge of Justinian, also known as the Sangarius Bridge, is a late Roman bridge with a remarkable length of 350 m, constructed to span the Sangarius River in the ancient region of Bit

Description

　　The Bridge of Justinian, also known as the Sangarius Bridge, is a late Roman bridge with a remarkable length of 350 m, constructed to span the Sangarius River in the ancient region of Bithynia in northwestern Anatolia. The bridge is located in the Beskopru neighbourhood within the Serdivan district, ca 5 km southwest of the town of Adapazari in northwestern Turkey. Today, the bridge spans the smaller Cark Deresi stream (called the Melas stream in Antiquity), which drains the nearby Lake Sapanca, whereas the modern course of the Sangarius currently lies 3 km to the

　　East. It was built by the East Roman Emperor Justinian I (527-565 AD) to ameliorate the transportation and communication between the capital Constantinople and the eastern provinces.

　　Considered one of the most significant late Roman and Byzantine emperors, Justinian aimed to restore the former glory of the Roman Empire through ambitious military campaigns and an empire-wide construction drive producing new religious, administrative and military buildings and structures. Located at the crossing-point of an important military road, hence the Bridge of Justinian had a geostrategic significance linking the western provinces and the Bosphorus to the eastern territories of the Roman Empire. According to various ancient sources including the De Aedificiis of Procopius that records the building projects of Justinian, this stone masonry bridge was constructed to replace an inadequate timber pontoon bridge that was frequently swept awayⁱ. Referring to the same sources, there is controversy in ancient references to the precise start date   of its construction but the construction of the bridge is known to be completed in AD 562.

　　This masonry bridge is made of limestone blocks, and has a length of 365 m, including the abutments at each end, with a width of 9.85 m and a height of up to 10 m. The bridge rests on seven central arches that have a span of approximately 23 m, which are complemented by five smaller arches serving as spillways in case the river overflows on either side, adding up to twelve arches in total. Based on earlier descriptions, the key stones of the main arches were decorated with single crosses in relief that are no longer visibleⁱⁱ. The central arches are supported by six piers of 6.5 m height and 6 m width, that have substantial buttresses serving as breakwaters. These piers are in rounded shape on the upstream southern side and are pointed on the downstream northern side. This significant feature differentiates the Bridge of Justinian from the majority of Roman bridges, which have pointed cutwaters facing upstream. Only on the western end of the bridge there are two low-pointed breakwaters situated both on the northern and southern sides.

　　The bridge structure was supplemented by an additional masonry structure attached to the south face at the eastern side, which partially blocks the adjoining small arch. According to Whitby (1985), this structure was built in two or more phases shortly after the construction of the bridge to function as a large breakwaterⁱⁱⁱ. It embodies a pair of vaults partially demolished, which is supported by five piers that are still standing. The masonry building technique employed in its construction and its workmanship is similar to that of the bridge and the piers are decorated with similar cornices as that of the buttresses.

　　As a representation of the majesty of the bridge, the nominated property also included a monumental triumphal arch that used to span the western entrance and the remains of a large apsed structure facing the bridge whose former function is unclear. In the illustrations of Léon de Laborde and the descriptions of Texier dating back to 1838, the triumphal arch is depicted as an arched entrance made of stone masonry that is approximately 10 m high and 6 m wide, supported with two pillars of 4.35 m thickness^iv. The apsed structure is considered to be constructed as a decorative parallel to the western triumphal arch but the situation of the apse towards east gives the impression that it might have been built as an open-air shrine. The 11 m high apse is covered by a barrel vault supported by two piers who are continued in the direction of the bridge. The bridge was also decorated with an inscription that has not survived today but which bears an epigram in Greek by Agathias^v.

　　In the Antiquities and Middle Ages, the bridge is known to have fulfilled its original purpose of linking the main Roman military highway to the east across the Sangarius. The river shifted to an easterly course later in the thirteenth century, probably into its modern channel, and its former channel traversed by the Bridge of Justinian was occupied by the minor Melas (Çark) river. Nevertheless, the bridge continued to function as an important passageway until the late 20th century, and contributed greatly to the formation of a urban settlement in vicinity, which was named as Beşköprü (Five Bridges) after the Greek name of the bridge, Pontogephyra.