The Rota Vicentia is 230 kms of trail along the southwestern coast of Portugal, much of it in the Alentejo region. There are really two routes, the inland route and the fisherman’s route. The fisherman’s route is recommended as one of the Best Places to go in Spring.
Not only is the project well signposted, the there’s an excellent English page: Rota Vicentina – Two Steps to Freedom.
The trail is meant to serve the public interest, but also has a marketing angle—which means services are being added all the time to provide trekkers with creature comforts. In that way it’s like the old pilgrimage trails, which were supplied by rich folks who couldn’t get to heaven unless they did something good with their money, which usually meant adding services like hospices to the route.
That means there are plenty of things to do besides walking on your trek.
Active travelers, check this out. Portugal has some of the more innovative travel progams in Europe.