It happened that I spent an afternoon in beautiful Sintra by chance of my first stop-over flight. While browsing the travel brochures, the image of beautiful castle got my attention. And based on the map it was within reasonable travel time from the airport. There are trains and buses going to Sintra from Lisbon. The trains leave from Rossio Station, Oriente, Entrecampos, Sete Rios and Campolide. I found that there are trains to Sintra approximately every 15 minutes from Rossio on weekdays and every 30 minutes on weekends.
From Sintra Train Station (Last stop) you can take bus 434 to reach the historic centre. You should keep in mind that main attractions are in the hills of the Sierra De Sintra and this hike is a good challenge! The bus makes a round trip taking visitors to Palácio Nacional de Sintra, Castelo Dos Mouros, Quinta da Regaleira and Pena Castle. The Palacio Nacional de Sintra is situated right in the heart of Sintra and often called the Palacio da Vila, the Town Palace. The most notable exterior features that became the icon of Sintra are the two massive chimneys protruding from the kitchens…
Of all the palaces built by the Portuguese monarchs throughout the Middle Ages, only the palace of Sintra has survived to the present day virtually intact. It is still maintaining the same essential features of its shape and outline since the mid-16th century. The National Palace of Sintra was designated a National Monument in 1910 and forms part of the Cultural Landscape of Sintra. It is classified by UNESCO as World Heritage since 1995.
The National Palace and its historical gardens are one of the most remarkable examples of the harmonious link between landscape and palatial architecture in Portugal.
The Palacio Nacional de Sintra was the preferred residence for King Duart. He spent much of his reign based within the palace. The popularity of the palace continued through to the 15th century when more lavish royal building were constructed. King Afonso V was both born and died in the Palacio Nacional de Sintra.
You may want to spend couple days or even more in Sintra area. There are nice beaches, lots to explore and enjoy. For more information here is the link:
http://www.sintra-portugal.com/index.html