40 Leadenhall Street is one of the largest projects ever to receive planning permission in the City of London – more than 900,000ft² of premium office space, able to accommodate 10,000 workers on floorplates up to 100m long. And a lot more besides: this is the office as destination, with restaurants, bars, fitness center, wellness suite and a clubhouse and events space, not to mention a statement 8m-high reception complete with a landscaped atrium.

Building anything in London’s historic center is always a complex feat of design, planning and execution. So this giant structure had to be woven through centuries of development above and below the ground, from its 12m-deep basement excavation, to the Grade II-listed heritage building that is integrated into the scheme, to the protected viewing corridors that determine the shape of all high-rise developments in the City. 

Working closely with Make Architects and the rest of the team, 58 separate design studies were completed during optioneering to overcome site constraints including lines of sight. Architect Make then created an elegant scheme of two towers rising from a shared podium, inspired by New York’s classic skyscrapers, with 17 outdoor terraces stepping down towards the River Thames. At ground level, it is set back from the site boundaries to carve out a new piece of public realm from this tight-knit street pattern, lined with shops. 

WSP’s multidisciplinary role began at the project’s inception back in 2013. The ambition to create a market-leading office never changed, but the demands of the market did. So our design for the structure and services had to evolve to incorporate new standards on wellbeing, air quality, connectivity and sustainability, to ensure that 40 Leadenhall Street would remain relevant as the world changed around it. 

40 Leadenhall is designed for the future of work – whatever that may be. This meant that the office floors had to be as free of structural constraints as possible, enabling tenants to configure, and reconfigure, the spaces in any way they wanted. 

WSP’s structural design supports this with very long, column-free spans. The building’s two cores have been pushed to the edges of the site, creating uninterrupted floorplates within the podium levels, achieving the best views for occupiers and supporting flexible layouts with floor-by-floor air handling in each zone. Our design also allows for future adaptation strategies – adding interconnecting staircases, for example, or converting amenity spaces to other uses.

Despite the constraints of this landlocked site, the development has created a new public space at ground level, with external circulation routes where previously there was only a narrow passage. The entire building cantilevers out from the first floor to hover above the extended public realm. 

All of this required many complex transfer structures – though occupants will never know. “The client’s aspiration was for huge flexible spaces without obstacles,” says WSP Director Rodolfo Giannini. “So none of the structural gymnastics are visible at all.”