So you're in the Baixa and you want to get to the Bairro Alto, high up on the hill? You have a couple of options: walk and sweat as you climb the hill that puts Montmartre in the shade; fight your way on to a packed tram.
Or you could take the metro station route. Yes, the station, not the actual train. The main entrance to Baixa-Chiado station is on the centre-city plain, but the "back door" is way up on Largo do Chiado, reached by a series of escalators.