Trajan's Bridge

Roman segmental arch bridge over the lower Danube

Trajan's Bridge, also called Bridge of Apollodorus over the Danube, was a Roman segmental arch bridge, the first bridge to be built over the lower Danube and considered one of the greatest achievements in Roman architecture. Though it was only functional for 165 years, it is often considered to have been the longest arch bridge in both total span and length for more than 1,000 years.

This keyword could refer to multiple things. Here are some suggestions: