Very much trying to be a designer shopping retreat today, but it remains a seaside resort. I think the casino in Estoril is still alive and running. Evidence of decedant past are very apparent everywhere and largely preserved. Fabulous buildings waiting for the right people.
Also some fabulously and surprisingly daring modern architecture. In fact, on the train all the way from Cais do Sodre in the centre of Lisbon to Cascais your subjective eyes will feast on boxes of special assortment just spilling down from the hills to the sea. If you are a lover of buildings in a very amateur context (like myself), or a more serious architecture enthusiast you will also love that train ride. It will be a post for another day. As will more Cascais info'. In the meantime, here is a sketch and a couple of pics with a Wiki link.
Here is what Wiki says
A view of one of the many small beaches. The building in the background is home to Christies.