Sintra

Sintra is probably the best day trip you can do from Lisbon. It is a really beautiful small town, well-preserved and surrounded by nice countryside. If you like a walk you can wander around the town for a while, and then head up the hill to the Moorish Castle which overlooks the town. It is a pretty pleasant couple of kilometres up, and the same back down again, but if you don't have time, or are just too damn lazy, you could get the scenic bus. At January 2006 this cost 2.50 euros for a hop-on hop-off ticket, and runs every 15 minutes or so in a circuit which goes past the station, through the town (including a stop outside the tourist information), and up the hill to the castle.