Estoril (Portuguese pronunciation: [ɨʃtuˈɾiɫ]) is a civil parish of the Portuguese municipality of Cascais, in central Lisbon. In 2001, the population of Estoril included 23,769 inhabitants, occupying an area of approximately 8.79 km² (3.39 sq mi).

The territory of Estoril has been occupied for centuries, owing to its climatic conditions and favourable environment. Throughout the civil parish there are scattered remains of these early communities; the Phoenicians, Romans and Arabs selected this area for its strategic place in Western Europe. There are remains of Roman villas in the parish, that extend the history of the region to the first millennium, when the settlements of the coast were dependent on the fishing ports. With these occupations, Estorial inherited a rich cultural patrimony, architecture, toponymy, habits and customs.

In 1147, during the Reconquista, the region was finally brought under Christian control.

Owing to its strategic place, the region was intimately linked to the Portuguese Age of Discovery, and all the dynamic social and cultural upheavals that it originated.