Constantine's Bridge (Bulgarian: Константинов мост, Konstantinov most; Romanian: Podul lui Constantin cel Mare) was a Roman bridge over the Danube used to reconquer Dacia. It was completed in 328 AD and remained in use for four decades.It was officially opened on 5 July 328 AD in the presence of emperor Constantine the Great. With an overall length of 2,434 metres (7,986 ft), 1,137 metres (3,730 ft) 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.