Lisbon has impressive public transportation. The metro is small but uber modern and connects easily to buses and rail. Lisbon also offers two iconic transport options. They have adorable yellow trams that run throughout the old city and due to the hilly nature of Lisbon (think San Francisco) they installed elevators in certain areas that will take you from one street and drop you off at the top of a hill. These elevators have become national monuments and are all very unique. Furthermore, you can buy an all day transit card for 5 Euro and use it as much as you want on any bus, tram, elevator, metro, (or ferry). You do have to buy an additional ticket to use the rail but it’s very cheap.
On our second day in Lisbon we hopped on tram 28 which seemed to be the popular thing to do. Tourists ride the tram to get a short tour of the city and locals still use the tram for their everyday transportation. There tends to be a little confusion when a bunch of newbie tourists try and enter or exit on the wrong doors (i.e. I almost saw an old Spanish Senora get run over by a tram when she had one leg in and one leg out) but you only make the mistake once and soon your hopping on and off like a local.
We rode tram 28 until the end of the line and decided to start walking up hill to the Castle Saint George which is in Alfama. Our trek was the back way up the mountain which was ideal. We saw different views of the city and had the route mostly to ourselves. The castle itself is a national monument and is very well maintained. You feel as if you are on top of the city and the views are worth the entrance fee.
And I forgot to mention…People jump on the back of trams and ride for free. There are no hand holds so they jam their fingers into the door…