A view from a boat heading down river towards Porto and Gaia during a Six Bridges Cruise on the River Douro. The boat is passing under the St John`s Bridge, the Ponte de Sao Joao and the cruise boat in front is approaching the steel structure Maria Pia Bridge, Ponte de D. Maria Pia, which was designed by Gustave Eiffel. The Ponte Infante D. Henrique Bridge, Ponte Infante D. Henriqueis is the concrete bridge in the distance.