© All Rights Reserved The 1876 Dona Maria Pia bridge in Porto. Designed by Gustave Eiffel, the bridge is the only one of the six bridges spanning the Douro that is not usedRelated images Session Room in the Dispatch House of the Order of São Francisco Panoramic View of Porto's Ribeira at Night Old riverside crane - Fluvial, Porto The Sé - Porto Chapel in Crystal Palace Gardens - Porto Miragaia Street - Porto