Pedras Salgadas Spa & Nature Park

While Portugal’s coast fills up with modernist-inspired beach resorts, the real architectural action is happening inland. Just over an hour from Porto, in a nature reserve that was once a royal holiday spot, is Pedras Salgadas Spa & Nature Park, which is more or less exactly what it sounds like — plus a hotel, of course, and a strikingly modern one at that, as a glance at the photos will make abundantly clear.

Architect Luis Rebelo de Andrade designed the twelve eco-houses to be built from prefabricated modules, resulting in accommodations which, though they bear a strong family resemblance, are all subtly different, largely due to their differing orientations to the site. The idea, sensibly enough, was to minimize the impact on the ancient forest, and, when inside, to maximize the impact of the views of the forest outside, from windows, skylights and open-air decks — and the two treehouses, self-supported on stilts above the forest floor, accomplish this goal with the greatest ease.

Meanwhile the 19th-century thermal spa has been subtly updated by another award-winning architect, the Pritzker winner Alvaro Siza Vieira, and the result is an inspired, and inspiring, space — not to mention an intensely restful one, thanks to the spa treatments and the thermal baths themselves.