The Oh Porto! apartments are situated within a Unesco World Heritage Site next to the Dom Luís I Bridge, which spans the Douro River between the cities of Porto and Vila Nova de Gaia.
The building contains five studio apartments and a penthouse to accommodate visitors to the city, and also houses a reception with a communal kitchen and an office space.
Local architects Nuno Melo Sousa and Hugo Ferreira collaborated on the proposal for the historically sensitive site, which involved overhauling and extending an existing building in a way that complements its context.
"Building on top of this area protected under the flag of Unesco with its charming historical character was a delicate process – a deep reflection made of very strong restrictions," the architects explained.
The original 19th-century building had received subsequent add-ons and had gradually fallen into a state of disrepair, so the starting point for the project was to reinforce the existing structure.
A concrete spine that extends the length of the long and narrow building provides additional support and enables the studio apartments on either side to be kept free of columns.
The new central section also contains utility spaces including the bathrooms, kitchens, elevators, lighting and vertical ducts.
The linear open-plan layout of the apartments ensures views in both directions. The sleeping areas of the studio apartments have views towards the city, while the kitchens and lounge areas at the rear look onto the rugged cliff or a concrete retaining wall.
On the upper floor, the two-bedroom penthouse features a full-height window with a sliding section that opens onto a balcony.
"From the inside, the building, reveals the structural and conceptual narrative," said the architects. "The concrete slabs and walls show the spine which holds the thick granite walls, with the existing windows as framed views."
A front door accessed from a steep, narrow street leads to a reception containing a simple plywood desk. Beyond this is the shared kitchen and office, which looks onto the granite rockface.
A new staircase leading to the upper apartments is positioned in the gap between the building and the cliff face. Its sculptural concrete structure complements the raw surface of the adjacent stone.
The stairs ascend to the penthouse, which is accommodated within a new addition clad externally in traditional tiles positioned to create a scale-like pattern.
The accommodation aims to provide a "minimalist concept with maximum comfort", according to a website promoting the apartments.
Wooden floors and fitted furniture throughout offer a simple and warm complement to the texture of the exposed board-marked concrete walls and ceilings.
Photography is by José Campos.