|Bond's Aston seen to the far left|
The small coastal town of Cascais featured in the pre-title sequence of On Her Majesty's Secret Service, covered here earlier, where Bond is seen driving down a coastal road in his Aston Martin DBS. The same curve in Cascais is seen again, very briefly, following the main title sequence, this time with Bond driving in the opposite direction.
Why Bond is seen driving in both directions on this road is unclear. It is possible that the intention was that you would believe that this is another road. However, it is fairly obvious that these scenes were shot in the same location.
Right next to this location is a fortress located, named Fortaleza da Nossa Senhora da Luz and the citadel of Cascais, which was part of the strategic defence of the coast.
This scene is partly integrated in the beautiful main title sequence and is seen just before Bond arrives at Hotel Palacio in Estoril. The action starts to play through the sand in the hourglass as the clock is counting backwards.
The road that Bond is seen driving down in Cascais is called Avenida Dom Carlos I and is located in the central part of Cascais, easily found along the coast.