It is the seat of the municipality of Sintra with an area of 319.23 km² and 381,728 inhabitants (2015), subdivided into 11 parishes. Its population represents 13.37% of the metropolitan total and 19.82% of the total in Greater Lisbon. The municipality is bordered on the north by the municipality of Mafra, on the east by Loures, Odivelas and Amadora, on the southeast by Oeiras, on the south by Cascais and on the west by the Atlantic Ocean. It acquires importance in the national context for being the second most populous municipality in Portugal, after the capital, and the town with the most inhabitants, followed by Cascais and Oeiras.
Geographically, the municipality is located at the end of the massif formed by the mountains of Aire, Candeeiros and Montejunto, topped by the Massif of Sintra, where its mountains and that of Carregaira stand out. The highest point in the municipality, which is also the one in the metropolitan area, is located in Pena, in the Serra de Sintra, and rises at an altitude of 528 meters. Surrounding them are platforms that do not exceed 200 meters and crisscrossed by several streams that demarcate the landscape.
Vila de Sintra is notable for the presence of its romantic architecture, resulting in its classification as a Cultural Landscape of Sintra, a UNESCO World Heritage Site and has refused to be elevated to the category of city, despite being the seat of the second most populous municipality in Portugal.