It was built by Jorge O'Neill in 1902, a direct descendant of the Royal Sovereign House of Ireland, who in the late nineteenth century, following the example of the Portuguese Court, chose Cascais as a summer resort. It is a project by Raul Lino, one of the most representative Portuguese architects of the twentieth century. Inseparable from the landscape of Cascais

With an architectural project by Francisco and Manuel Aires de Mateus and a museum program by Joaquim Boiça, the Santa Marta Lighthouse Museum was rehabilitated based on a protocol signed between the Cascais City Council and the Portuguese Armed Staff. Opened to the public in July 2007, its model is unheard of in the country, combining exhibition spaces with the coastal signaling function, overseen by the Directorate of Marine Lighthouses. With the exception of the cannonball found in the town's archaeological excavations, the collection of the Santa Marta Lighthouse Museum was entirely restored and deposited in the Lighthouse Museum by the Portuguese Navy / Lighthouse Directorate.

The Condes de Castro Guimarães Library Museum is housed in the building initially known as the “Tower of S. Sebastião”, built in 1900 by Jorge O'Neill according to the project by painter Francisco Vilaça. In 1910 the building was acquired by the Counts of Castro Guimarães who, in 1924, bequeathed to the people of Cascais the “Torre de S. Sebastião”, the objects of art and books, to set up a Municipal Museum and Public Library. enjoyment of the population.

In 1992 the Museum of the Sea was inaugurated, a space dedicated to the sea and its people. The museum is organized by thematic exhibition centers: Cascais on the Shipwreck Route, dedicated to underwater archeology; Biodiversity, where we find specimens of fish, mammals and waterfowl, shells and marine fossils; Gentes do Mar, dedicated to the uses and customs of the fishing community of Cascais, as well as traditional fishing arts; Navy and Navigation, which focuses on historical and technical aspects; Marine Fossils, where the museum's collection of marine fossils is on display and, finally, the D. Carlos nucleus and Oceanographic Science that reconstructs the main moments of the action of the king and his team aboard the Amelia yacht.

Inaugurated in May 2000, the Cascais Cultural Center is housed in the "Pink House", former Convent of Nossa Senhora da Piedade. The construction of this Convent was the initiative of the 4th Count of Monsanto, D. António de Castro, who wished to install the first Portuguese College of Philosophy. The works were completed in 1641. Almost completely ruined by the 1755 earthquake, the Convent was not rebuilt. even if the brothers continued to inhabit it. The history of the Convent until 1834 is described in the Chronicle of the Discalced Carmelites, a religious order that occupied it until that date. When this year the religious orders were abolished, the convent was abandoned and ruined. After passing through several owners was acquired by the Viscount da Gandarinha, in the late nineteenth century, who had installed his summer palace there.

Considered a splendid white-sand beach with its proximity to countless shops and charming shopping streets and its cosmopolitanism, the fishing village of Cascais has reinvented itself and has become a refined seaside resort and one of the most sophisticated destinations in the Lisbon area. . The town, located a few kilometers from the mouth of the Tagus, is nestled between the sunny Cascais bay and the majestic Serra de Sintra. It displays a delightfully maritime and refined atmosphere, attracting visitors all year round.

Located on the west coast of mainland Portugal near the village of Cascais, it may have been a cave in very ancient times. Being the region formed of carbonated rocks, the action of rainwater, with dissolved carbon dioxide, progressively over time dissolved the carbonate. In this way cavities were formed in the rocks that, with the action of the sea force, were progressively increasing in size. The abatement of the upper layer turned the cave into an open pit. The current look, along with the sound of the waves crashing against the rocks and the foam that often rises up to the level of the road, justifies its name as Hell's Mouth.