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