There are two ways to be married in the Algarve, and picking the right one early saves months. The first is a Portuguese civil marriage: a real legal marriage, registered by the Portuguese state, recognised at home when you land. The second is a symbolic ceremony: you complete the legal marriage in your own country, usually in a ten-minute appointment at a register office, and the ceremony in Portugal carries no legal weight at all. Most international couples take the second route.
The civil route is not difficult, but it is a documents exercise with a clock on it. You do not need to live in Portugal, and you do not need to have set foot in the country before you file: the Embassy's guidance is explicit that "being a resident is not a requirement to marry", and that an attorney holding a power of attorney can start the process on your behalf. What you do need is paperwork that is recent, apostilled, and in Portuguese.
The application goes to a Civil Registrar Office, and it can be any Civil Registrar Office in Portugal, not the one covering your venue. Processing takes a minimum of four weeks. Once the registrar approves it, you have six months to hold the ceremony, which is a wider window than most couples expect and worth using.



