Obidos is a beautiful old fortress town enclosed by a wall.  The streets are filled with gorgeous white buildings adorned with climbing bougainvillea.  We meandered through, and then hit the town square for an amazing sangria and cheese/charcuterie lunch.  It was phenomenal. I think this is one of the best (definitely the prettiest) of towns to stop in Portugal.  I recommend you either get there super early, or after lunch around 1 or 2 to miss the giant tour buses that bring gobs of tourists.