When in Oporto, of course you must see the Port Wine cellars, they're actually all across the river in Villa Nova de Gaia, but all offer tours; we paid (not much) for the tutored tour at Crofts and it was fantastic, I highly recommend it. Also, in Oporto, since it's under massive reconstruction due to it's declaration as a UNESCO world heritage site...don't take/hire a cab!! There should be a tram from the port into the core, and from there WALK!! No place worth seeing is very far.

Regards,

John Wiernikowski Hamilton, ON CANADA