The coastal settlement of Cascais originated in the 12th century, depending administratively on the town of Sintra. In its humble beginnings, Cascais lived from the products of the sea and land, but already in the 13th century, its fish production served the capital Lisbon, located nearby. During the 14th century, the population increased to the outside of the walls of its castle. Its prosperity led to the administrative independence from Sintra in 1364.

 

Since the Middle Ages, Cascais lived from fishing, maritime commerce (it was a stop for ships sailing to Lisbon) and from agriculture. Due to its location close to the Tejo estuary, it was also seen as a strategic post in the defence of Lisbon. Around 1488, King John II built a small fortress in the village, located by the sea. This medieval fortress was not enough to repel the invasion and in 1580, Spanish troops led by the Duque of Alba took the village during the conflict that led to the union of the Portuguese and Spanish crowns. The fortress was enlarged towards the end of the 16th century, turning it into a typical renaissance citadel with the characteristic flat profile and star-shaped floorplan. Various fortresses were built on the coast around Cascais during the 17th century, and many of them still exist.

 

Another important step in the touristic development of the area was given in the first half of the 20th century in neighbouring Estoril, in which a casino was built and the infrastructure for luxury vacations was created around Monte Estoril.

Due to Portugal`s neutrality in World War II and the town`s elegance and royal past, Cascais became home to many of the exiled royal families of Europe, including those of Spain, Italy and Bulgaria.

Nowadays, Cascais and its surroundings are a famous vacation spot for the Portuguese and foreigners, aiming at both the "jet-set" and normal tourism, who seek to enjoy its beaches.

Cascais is surrounded by popular beaches, such as Guincho to the west, and the lush Sintra mountains to the north. Some of its shoreline is cliffy, attracting tourists for its seascapes and other natural sights such as the Boca do Inferno (Hell`s Mouth). It is also becoming a popular golf destination, with over 10 golf courses nearby. Surfing, sailing, windsurfing and kitesurfing are also popular in the region around Cascais due to favourable weather, wind, and sea conditions. In 2007, Cascais was the official host of the ISAF World Championship in sailing for dinghies and racing yachts.