Ian Fleming, the writer of James Bond’s novels, was part of the British Naval Intelligence Division and became inspired to create special agent James Bond during a stay at the Palácio Estoril Hotel and during some of his evenings at Casino Estoril watching spies who gathered there during World War II.
During the Second World War, as Portugal was a neutral country, Casino Estoril became a place frequented by spies and exiles, including members of some deposed royal families.
In On Her Majesty’s Secret Service, James Bond, prevents a young woman, Tracy Draco, from committing suicide. Her father is the leader of a powerful crime organization, and he wants Bond to protect her by marrying her. The wedding scenes were filmed at the Palácio Estoril Hotel, and in the gardens of the Estoril Casino, which is still the biggest casino in Europe.
You can see some scenes here: https://www.youtube.com/watch?v=26E__jS0AVU , or by visiting Estoril during your next trip to Portugal!