Constantine's Bridge (Romanian: Podul lui Constantin cel Mare; Bulgarian: Константинов мост, Konstantinov most) was a Roman bridge over the Danube. It was completed or rebuilt in 328 and remained in use for no more than four decades.[4] It was officially opened on July 5th, 328 in the presence of the emperor Constantine the Great.[1] With an overall length of 2437 m, 1137 m of which spanned the Danube's riverbed,[5] Constantine's Bridge is considered the longest ancient river bridge and one of the longest of all time.[6]