A striking new development has emerged on London’s Finchley Road, featuring towers constructed from massive, rugged blocks of pink basalt and igneous larvikite. Rising next to the Finchley Road & Frognal station, these structures serve as a distinct, geological landmark that stands in stark contrast to the standard apartment buildings often found above local transport hubs. Architect Amin Taha, who designed the project, describes the towers as an unmissable point of reference for commuters who often struggle to locate the station. Shooting skywards to form teetering towers, great chunks of pink basalt and igneous larvikite appear to have exploded from the railway cutting. Anyone trying to find Finchley Road & Frognal station need wonder no more: just look for the multistorey Stonehenge. A result of public transport-oriented policies, but none have looked like the Flintstones were in charge, countless apartment towers have sprouted above London’s stations in recent years. According to “This is one of those stations where people are always scratching their heads trying to find it,”, Architect Amin Taha, standing at the foot of his rocky megalith, an unmissable landmark next to the Overground entrance. “We’re unlikely to start building church spires or grand civic buildings with clocktowers again, so we wanted to make something people could point to and say, ‘It’s next to that building.’”. The igneous rock that holds up these flats has been stacked with deceptive simplicity. You never quite know what the finished result will look like, and the beauty is. According to perhaps more architects should sign their buildings, so passersby know where to direct their praise – or ire. “The common reaction from developers is that structural stone is too shocking,”, Taha. “They think the Bri. With chunks of stone bulging out at points in bouldery lumps, it rises above the station platform like an elemental cliff. The stairway is open to the elements and spills on to a lush communal roof garden, all adding to the feeling of hiking up a rocky mountain path, wrapped with steel mesh. But even Taha’s clients have their limits, you half expect the lift itself to be a hollowed-out boulder winched up on a rope.
Known as Petra Heights, the three towers—ranging from six to 10 storeys—utilize solid stone as a primary structural element. Each slab weighs approximately three tonnes and retains the drill and saw marks from the quarry, a deliberate design choice that Taha says saves the energy and costs associated with cutting material into standard, clean-cut forms. Taha notes that the aesthetic is unpredictable and raw, avoiding the typical polish expected by many developers. According to building a trio of six- to 10-storey towers out of solid stone may sound like an expensive proposition, but Taha, It is not only cheaper but saves a huge amount of carbon emissions compared with a concrete or steel-f. Webb is fiercely critical of the scourge of carbon-hungry bricks as the default. “Bricks are the heaviest form of decoration you can imagine,” he says. “They require a huge amount of energy to fire – often using coal – a. In the last 10,000 years of building history, he argues, walls have held the floors up. Petra Heights is their biggest proof of concept yet.
The project represents a significant shift for Taha and his collaborator, engineer Steve Webb, who are advocating for a return to load-bearing stone. The construction process saved roughly 30% in carbon emissions compared to traditional concrete or steel-framed buildings. Had the internal frame been built with cross-laminated timber as initially planned, Taha estimates that the saving could have reached 75%. This effort follows their previous work on the Clerkenwell Close residential and office project, which was shortlisted for the 2021 Stirling prize for its use of stacked limestone. Creating experimental stone beams, laminated vaults and floor slabs, using pieces of rock that quarries often treat as waste, the duo have become evangelical about the wonders of stone.
The assembly of the towers was rapid, with the stone lift shaft—a world first—reaching its full height in a single day. The slabs, measuring 10cm thick and three metres high, were shipped from Norway and assembled on-site. Despite the ambitious vision, the project faced several hurdles since its 2015 inception, including multiple changes in ownership and pandemic-related supply chain disruptions that required a shift from Sicilian basalt to Norwegian larvikite for the upper floors. The project had a bumpy ride, originally designed in 2015. Which taper as they climb, are connected to a central lift and stairs, and joined by a precipitous bridge at the upper levels, the three towers.
Engineer Steve Webb is a vocal critic of the industry’s reliance on carbon-intensive brickwork, which he characterizes as inefficient and weak. He argues that modern construction has moved to an illogical state where floors hold up walls, rather than the traditional historical method where load-bearing walls support floors. To demonstrate the potential of stone, the team worked on a temporary stone demonstrator house in Earl’s Court, commissioned by the Design Museum’s Future Observatory. This structure utilized pre-tensioned beams and columns to achieve a 90% carbon reduction compared to standard methods.
The innovations extend to upcoming projects, including a mixed-use development in Hackney that Taha expects will be carbon negative. This building will feature stone bricks and dowel-laminated timber, combined with canal water source heat pumps and photovoltaic shading to generate 135% of its required energy. Meanwhile, Webb is currently designing a 200-metre tower near Liverpool Street that utilizes load-bearing stone to eliminate the need for a massive concrete core.
Looking toward the future, Webb views the integration of structural stone as a major opportunity for architects to innovate, drawing parallels to the evolution of the first iron bridge in Telford. He envisions a future where stone is used for infrastructure like electricity pylons, leveraging its natural stiffness to reduce reliance on steel. As the foliage on the Petra Heights facade grows over time, the towers are expected to further resemble an ancient, integrated ruin, marking a potential dawn for a new era of stone-based construction. Webb’s firm, Webb Yates, has even developed a slender pylon prototype, exhibited at the Royal Academy, using stone’s stiffness and buckling stability to reduce the amount of steel required.
