The Sintra National Palace is the only surviving Royal Palace from the Middle Ages. Very likely, it was built on the residence of the former Muslim wallis and since the beginning of the Monarchy the Palace was a royal residence. The main building programmes carried out by King John I, which rebuilt the Palace, and by King Manuel I, which added the now called Manueline Wing, granted the Palace its present look.

The chapel, rearranged during King Manuel's programme, is built in the Mudejar style, after the Hispanic-Moorish glazed tiles coating on the walls, which is one of the few evidences of this style in Portugal. From those first two periods, the kitchen is to be stressed, with its two chimneys 33 metres high, and so are the Arab Room, partially coated with glazed tiles of geometrical matrix, or the magnificent Central Patio, with its laced semidetached arches adorned with flounces.

During the Modern Age the Palace didn't stop to expand, as the Renaissance elements of King John III' s time give evidence of: the large Swan's Room, the oldest ceremony room of the Portuguese Palaces, where the portraits of Catarina de Bragança, Charles II of England and Peter II are on display; the Coat-of-Arms Room, whose dome shows King Manuel's arms, his sons' and of seventy-two families' from the Portuguese nobility, and whose walls' entire coating dates back to the 18th century, a work of the Lisbon glazed tiles Great Masters Cycle of that time.

Severely damaged by the Earthquake in 1755, the Palace was rebuilt "in the old manner" and during the 19th and the 20th centuries went through numerous works which definitely changed some parts of it, as the buildings that closed the Largo Rainha Dona Amélia (Queen Amélia Plaza), which had also been destroyed then. The Palace has been a Museum since 1940 and in 2007 the Palace was put under the guardianship of Instituto do Museus e da Conservação (a Ministery of Culture agency) along with Ajuda, Queluz and Mafra National Palaces and also Paço dos Duques, thus asserting its role as a museum-palace. 

The Sintra National Palace was declared National Monument by decree in June 16th, 1910 and is today one of the most visited monuments in Portugal. The Palace relates to the monumental area designated in December 6th, 1995 by UNESCO as Sintra Cultural Landscape, inscribed in the World Heritage List.