Constantine’s Bridge was officially opened in the presence of emperor Constantine the Great (who ruled Rome between 306 and 337 AD when he was acclaimed emperor after his father’s death). This was a 2,437 m Roman bridge over the Danube, 1,137 m of which spanned the riverbed, that is currently considered the longest ancient river bridge and one of the longest of all time — especially considering it was a wooden arch bridge with wooden superstructure (with masonry piers). [The longest pure arch bridges today barely exceed 500 m’s in length.]
While it only lasted four decades (which is still impressive given its mostly wooden construction), it is still a feat of ancient engineering and an accomplishment in logistics as it allowed for horse and cart delivery of goods (and men) in place of boats.