If you find yourself travelling from Lisbon to Porto, I recommend laying over for 24 hours in the Historic University town of Coimbra.
The Old University area and the old town are a delight to wander around.
Not only is it home to one of the oldest Universities in the western world, but its location on the Mondego River is picturesque!
I also recommend visiting Fado do Centro to hear the traditional male student fado from Coimbra - http://www.fadoaocentro.com/
Here's a clip showing my acquaintance, João Farinha and his colleagues singing the famous traditional Coimbra Fado, "Coimbra", while strolling the old streets of Coimbra.
For accommodation have a look at:
Hotel Victoria -
http://www.residencialvitoria.net/ - Very Central and personally recommended.
Ibis Coimbra -
Restaurant -
Cozinha da Maria
