There are two options to run along the Douro River to the beach in Porto: the Foz side or the Gaia side. This 6.3 km one-way run is on the Vila Nova de Gaia side, which some argue is the prettier of two options, with views of the river and Porto on the right as you head toward the ocean.
Start at the Luiz 1 Bridge. Run along the river, near the Mosteiro da Serra do Pilar (hillside monastery), and head west toward the ocean. There is a good sidewalk or dedicated pedestrian path the whole way. Stairs lead between the river and the road, at points. At the 1 km mark is a cable car that runs up the hillside. At 2 km is the Arrábida Bridge, and the Harbor Bridge Climb. you can climb up the stairs to the bridge. The last third of the run is along the estuary where the Douro runs into the Atlantic. Great views.
This is a healthy 12.5 km (6.8 mile) out and back. You can also shorten the run by turning around at any point.
Add-On: Continue along the beachside path, heading south.Add-On: Gaia Seafront Path