Pedras Salgadas Spa & Nature Park

As luck (and a mutual friend) would have it, one of the first people I met when I moved to Lisbon a little more than five years ago was the architect Tiago Rebelo de Andrade. He told me then about a project he had worked on with his architect father, Luís Rebelo de Andrade, that was revolutionary at the time. The two had dreamed up Portugal’s first tree house hotel project, in the Pedras Salgadas thermal park in the far north of the country.

Immediately, I wanted to visit the place. But then a whole lot of other things happened. I kept jetting off around the world (at least until everybody stopped going anywhere) and getting deeper into other parts of Portugal. it took me five years to visit the place that I had put on my must-visit list within weeks of arriving in this country.

It was worth the wait.

The place is an alluring mix of nature, turn-of-the-century grandeur, and modern, nature-focused architecture. It got its start as a thermal wellness resort in the 19th century, when people drank the lightly effervescent water from the mineral springs as a cure for a slew of ailments. (When I asked in the water museum if Agua das Pedras, now widely sold around the country—the Pellegrino of Portugal—was still believed to do all that, my dry-witted Portuguese travel companion said, “I suppose so, but now we just take medicine.”)

Although there is still an old-school thermal spa (reinvented by noted architect Siza Vieira) on the premises, most of the wellness now takes the form of forest bathing. The property covers some 20 hectares, a dense ecosystem with 27 species of trees—from giant sequoias to Chinese firs—red squirrels, white storks, gray herons, spotted woodpeckers and, sometimes, snowy egrets.

That’s why “we thought it was important to respect the landscape,” says Luís, of their entry into the design competition that was held when the property was acquired by Unicer (currently the Super Bock Group, a beverage company) in the early 2000s. The owners’ idea was to work with two of the old hotels that still existed on the property. The architects proposed demolishing one of them, except for the ground floor, which now contains much of the property’s infrastructure, and building a small mountain on top to conceal it.

They intended to refurbish the other old hotel, but first they proposed some new bungalows—eco houses, as they call them—that could be built quickly and rented to guests as the larger renovations took place. The owners liked this idea, particularly the part about generating revenue more quickly, but also the part about how the houses’ modular design allows the floor plans to be configured differently so that no trees had to be cut down to make room for them. (That other refurbishment never happened, although they did do a rather snazzy job with the old casino.)

With that settled, the architects pushed further. “One day in a meeting with the administration, I said, ‘You’re always speaking about families and green tourism,’” recalls Luís. “‘’Who wished they had a tree house when they were young?’ All but one hand went up.”

Still, it took some convincing, because there was absolutely nothing like it at the time. But that was the point. “We wanted something different from what people were used to,” says Luís. Still, “it was complicated to persuade the client,” recalls Tiago. “We did a lot of presentations and videos.” Eventually the architects took their client to the revolutionary Tree Hotel in Sweden.

The two tree houses—or “snake houses,” as Luís prefers to call them, because they don’t actually rest on tree branches (too fragile) but are on stilts, and because their elongated shape, with a widening on one end, is vaguely cobra-like—live surprisingly well. They’re quite compact, as they were fabricated off-site and brought in on flatbed trucks, but organized efficiently.

Each one has a comfy bed in front of and below big windows onto the forest. There’s also a small table, a couch, and a compact but functional closet and bathroom with a shower. It’s everything you need, at least for a few days. And because they’re reaches by flat bridges from the top of that artificial mountain, they’re accessible for all. (A member of the architects’ family is disabled, so they think about such things.)

Apparently the marketing department agreed with me that the “snake house” name might be off-putting, even though Luís is sticking to it—“only pigeons should be afraid of snakes,” he insists. Everyone else promotes them as tree houses.

Including Tiago, when he put them “all over the Internet” and pitched them to publications like Dezeen, Wallpaper, ArchDaily and Travel + Leisure, which gave Pedras Salgadas a design award for best hotel in 2014. Soon Portuguese emigrants were coming back to see this cool project that had taken flight in their homeland. Then design lovers from around the world followed. Now the tree houses are booked out three months in advance, during high season.

They put the village of Pedras Salgadas back on the map. “The people there love my father,” says Tiago, because their project drew people from far away to see their architecture, which gave rise to a number of tourism-related businesses in the once-dying village. They’ve proven that sustainability is about far more than recycled materials and the preservation of trees. It’s sustaining a community.