For 2,000 years the most durable spanning structures have been built of masonry, and the surviving bridges of the Roman Empire have challenged master masons, architects and engineers to emulate and surpass them. Down the centuries, bridge-builders have been commissioned by monarchs, bishops, councils of state, cities, private individuals and, more recently, waterway and railway companies. The studies collected in this volume focus chiefly on the bridges, viaducts and aqueducts themselves and the actions of the designers and builders, but also encompass the political, economic and social contexts and outcomes of their creation. Famous bridges in Britain, Italy, France, Iran and the USA are all featured. Narratives of conception, design and construction predominate, but there are also papers on construction techniques, on the analysis of documentary sources, and on the continuing search by modern engineers for satisfactory scientific description of the strength and stability of arch bridges.