There are at least a few day trips well worth doing when in Lisbon, Portugal. One of them is definitely Sintra - a small town situated 30 kilometers west of the capital. It is dotted by royal retreats, estates, castles and buildings. The fact it was classified by UNESCO as a World Heritage Site in 1995 can only give you an idea how special this place actually is.
The top attractions of Sintra are: the Castelo dos Mouros, the Pena National Palace, Quinta da Regaleira and the Sintra National Palace. The Pena National Palace (summer residence of the monarchs of Portugal during the 18th-19th century) is definitely the thing that impressed me the most. It looks magnificent from the outside and when you walk through its front gates it feels like you have just walked into a fairytale. Details are simply breathtaking.
I should probably also mention a vast collection of artifacts from the time this place was still in use by the royalty. Definitely worth a closer look.
Large areas around those palaces are actually quite nice parks one could spend days exploring. Some parts with large boulders, tall trees and ancient fountains are especially beautiful.
Also views from both the walls of Pena National Palace as well as Castelo dos Mouros are something not to be missed. Even though it was cloudy and foggy on the day of our visit it was well worth it - the mist made it all feel even more magical. I can hardly imagine the views on a clear sunny day.
Since Cabo da Roca - the westernmost point of continental Europe is just a few kilometers further to the west, we decided to squeeze both of these attractions into the same day. This is definitely doable if you do not intend to visit everything Sintra has to offer and just wish to get a feeling of the place. Just make sure you start really early.
If you like to explore historical sites in detail, you should probably reserve at least a couple of days for Sintra - there are simply so many interesting things packed into this little town you will have
Cabo da Roca is nothing so special - you can find a lighthouse, a monument and a restaurant there on the top of some cliffs dropping down to the ocean. Nevertheless, it is the end of earth and for this fact alone it attracts crowds of visitors year-round.
We took a train from Lisbon (Rossio train station) to Sintra and caught a bus which took us to Cabo da Roca. From there we returned to Lisbon via Cascais (by bus), where we changed to a train. Cascais is a seaside city we unfortunately did not have time to explore.
We opted for an all-inclusive day travel ticket, which we used for the round trip and it also included buses linking various attractions in Sintra. You should keep in mind those attractions are scattered on quite a large area in and around Sintra and placed on neighboring hilltops (you can check out the area on this map).
If you are not a fan of public transport there are also many car rental companies in Lisbon offering good deals. As I was told prices are supposed to be really affordable, especially in the off-season.
Another interesting day trip we did not manage to squeeze into our schedule is a trip to Evora. Evora is another UNESCO World Heritage Site located approximately 135 kilometers to the east of Lisbon. I definitely recommend you to take a look into it if you have enough time.