Dom Luís I Bridge — Top Deck Walk (Ribeira)

The Eiffel-disciple Théophile Seyrig designed this in 1886 and the upper deck is now the metro line plus a pedestrian walkway. Walking across the top from Porto to Gaia, especially at sunset, is one of the better hours you can spend in this city. The view back at Porto's tiled facades catching the last light is the postcard. Free, takes 15 minutes one way, and the Gaia side has the wine cellars and the funicular back down. What to order: Nothing — it's free. Bring a glass of vinho verde from the Ribeira side and drink it as you cross.