Sintra is a beautiful town located about 28 km (30-minute drive) from Lisbon. It has been a long time royal sanctuary and is home to several pastel-coloured castles and palaces, as well as its many 19th century Romantic architectural monuments.
I highly recommend you spend an entire morning until afternoon here and visit some of the castles and palaces in this area, and stop by the coastal town of Cascais on the way back to Lisbon for a late lunch (or early dinner) while enjoying its stunning coastal views.
Pena Palace: This is a Romanticist castle that was built in the Middle Ages and stands on the rock in the Sintra Mountains. It also has a mixture of eclectic styles such as Neo-Gothic, Neo-Manueline, Neo-Islamic, and Neo-Renaissance. For centuries Pena Palace was used for meditation, housing up to 18 monks. This palace and the entire cultural landscape of Sintra were classified as a World Heritage Site by UNESCO in 1995. It is sometimes used for state occasions hosted by the Government.
Castle of the Moors: Constructed by the Moors in the 8th and 9th centuries, this medieval castle was an integral strategic point during the Reconquista period. It was then taken over by the Christians after the fall of Lisbon in 1147. In 1375 King Ferdinand I ordered the rebuilding of the castle. But the 1755 earthquake caused significant destruction and has been abandoned ever since. At the end of the 19th century several restoration projects were authorised to try to keep the castle from further ruins. There were continuous efforts over the centuries, such as the ones in 2001 where several intervention acts were introduced with the intention to preserve the castle. Today, it is a very popular site for tourists.
Palace of Sintra: Also known as the Town Palace, this was built around the early 14th century by King Dinis I, and was occupied from the reign of King John I during 15th century, and it continued to be inhabited by Kings from time to time during the following centuries. When Portugal became a Republic in 1910, this castle was turned into a National Monument. Today, Palace of Sintra is the best-preserved medieval royal residence in the country, and is used a historic house museum.
There are several other palaces and mini castles in the area, such as Quinta da Regaleira (below), Monserrate and Quinta do Relogio that are also open to the public.