Wine, wine, wine
Gaia is not a touristy destination, but no visit to Porto would make sense without crossing the bridge.
They should call it "Gaia wine", instead of "Port wine". All the great producers line the river in Gaia waterfront. Which one should you choose?
Well, they all offer from the common Port to the excellent one, so that's up to you, and if you are extremely exquisite and want to
identify the differences, no problem, two months of intensive daily tasting should be enough.