The Romans were the first great builders of bridges in the western world. Professor O'Connor, a civil engineer and expert in bridge construction, has examined a very large number of those bridges that still remain all over the Roman empire. In this book he presents a thorough listing and description of all known bridges, in many cases illustrating the construction of the bridges by his own photographs and sketches. Introductory chapters place the bridges in their geographical and historical contexts, with detailed maps of the empire-wide system of Roman roads and discussion of how these came to be constructed, and an investigation of the technology available to the Romans. Finally, in order to elucidate the principles used by the Romans in designing their bridges Professor O'Connor examines the proportions of the stone arches, and subjects the rules that emerge to modern structural analysis.