A sweeping roof inspired by the mountain skyline of the Alps defines a hillside extension to the Olympic Spa Hotel by Network of Architecture.

Designed to be "in symbiosis" with the landscape, the addition to the hotel in the Dolomites in Val di Fassa, Italy, houses ten new guest suites and a gym. An aerial walkway leads to an elevated timber sauna, also designed by Network of Architecture.

The new spaces were commissioned by the Pellegrin family, which has operated a hospitality business on the site since 1963.

"[The] new extension [aims] to enhance and integrate the facilities with the surrounding landscape," NOA told Dezeen. "[The] project camouflages the new, plays with the profile of the mountains and gives guests the emotion of [a] sincere bond with nature."

The hillside site slopes down to a forest and stream. An existing four-storey chalet housing the main hotel sits atop the hill to the west.

NOA's design placed the extension to the east of the existing hotel, partially burying the new rooms into the slope, overlooking the forest. An underground passage connects them back to the hotel.

The new building is characterised by its mountain-like profile, with a double-height spike at one end identifying the largest suite. The roof profile descends from this point, with smaller spikes indicating the rest of the suites and the gym.

"This silhouette, highly recognisable in its graphic simplicity, is intended to become the hotel's architectural signature," explained the studio.

The grey of the reinforced concrete used in the extension's structure is reminiscent of Dolomite rocks, helping to tie the building into the landscape.

All of the new suites have expansive windows and a large terrace overlooking the forest.

In their interior, the rooms are inspired by the natural landscape, with four paying homage to the forest, and the remaining five influenced by water.

The "Te Bosch" forest rooms are characterised by internal patios with glazed walls that bring light and nature into the spaces. Each patio gives views of the sky and houses a birch tree.

Conversely, the "Te Aga" water rooms have stone fountains and external tubs for bathing.

The largest suite is housed in the "peak" of the building and spread over two floors, with a sleeping area on the ground floor, and a relaxation area with a sauna and wellness area in the loft above.

All the suites make use of locally sourced oak and larch wood for their floors and furnishings.

"The emphasis is on direct contact with nature, which is also supported by the used materials, by the facade design that plays with the mountain skyline, by the terraces and the special interior patios embedded in the larger rooms," explained the studio.

A new elevated sauna positioned to the south of the site gives eye-level views of the surrounding tree canopies. It has a similar jagged profile to the hotel extension, responding to the mountainous landscape.

Made of wood and clad in larch, the sauna aims to blend into the forest. Internally, the sauna is clad in spruce treated with black wax. It is accessed from the hotel via an external aerial walkway.

"Access to the sauna is only outside, even in winter: a choice that intends to promote strong and direct contact with nature," said the studio.

NOA is an architecture and design studio with studios in Bozen, Milan and Turin in Italy, and in Berlin, Germany.

The studio has completed several other additions to hotels and resorts across the Alps, including a wellness area resembling an upside-down village, and a timber-clad hotel in an Alpine Meadow.

The photography is by Alex Filz.