© 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 Ribeira - Porto Teatro Nacional São João River Douro View from Ribeira to Arrabida - Porto Fountain - Crystal Palace Gardens A Pérola do Bolhão Delicatessen - Porto Panoramic View of Porto's Ribeira at Night