The Douro River starts in Spain, and empties into the Atlantic at Poro. We took a day trip beginning with a train ride up the river, and then most of the day returning, with incredible views of the vineyards and towns along the way. There was a massive lock that must have dropped 100' or more that was a highlight.
We did so much walking - 18 miles one day! Lisbon is a mix of old and new, smart and run-down, centered around the river. Good food, lots of hills for views, and we did an interesting city walking tour.
The food here was so good. We were fortunate to stay in an apartment right by the river, with easy walking to downtown, and just across the river from the port companies. We enjoyed a tour and tasting at Sandeman.