Trajan's Bridge or Bridge of Apollodorus over the Danube was a Roman segmental arch bridge, the first to be built over the lower Danube. Though it was only functional for a few decades, for more than 1,000 years it was the longest arch bridge in both total and span length. The bridge was constructed in 105 AD by Greek architect Apollodorus of Damascus for the deployment of Roman troops in the war against Dacia.