Justinian's bridge over the Sangarius and the date of Procopius' de Aedificiis
In the village of Beşköprü, about five kilometres to the south-west of the town of Adapazari in western Turkey, and just to the north of the main Istanbul–Ankara highway, there stands a large well-constructed bridge; its fabric is generally in good condition apart from the destruction of a short section of the causeway near its eastern end to permit the passage of the branch railway line to Adapazan. Although the bridge now only spans two minor side channels of the small stream called the Çark Deresi, which drains Lake Sophon (modern Sapanca), there is no doubt that the bridge was originally designed on the orders of the emperor Justinian to span the mighty Sangarius (modern Sakarya) which at present flows in a south–north direction about three kilometres to the east of the bridge. The only detailed first-hand account of the bridge is still that by Texier, whose description has to be corrected on some important points.