In a surprising but quietly strategic move, Mace has been appointed as the principal contractor to transform the now-vacant City Hall building in Southwark—Norman Foster’s controversial glass egg—into a sleek, mixed-use office and retail space. The Greater London Authority headquarters, vacated in late 2021, is at the heart of a regeneration plan that aims to preserve architectural flair while delivering practical, modern urban space. This week’s decision marks a critical step in repurposing one of London’s most distinctive and debated landmark designs.
Foster’s building, with its spiralling walkway and skewed façade, has been a visual symbol of early 2000s architecture—but also a lightning rod for criticism, from energy inefficiency to impractical layout. Since the GLA’s relocation to Newham’s “Crystal” building in 2022, the original site has stood largely empty, except for fleeting cinematic cameo appearances. Now, developers St Martin’s Property, together with architectural firm Gensler and LDA Design, plan to smooth its southern slant, replace the glass exterior, and extend its footprint by approximately 14.2 metres—adding around 3,800 sqm of new capacity, roughly 3,300 sqm of retail and 452 sqm of office space. These plans won approval from Southwark Council in December 2024.
Mace’s role is an elegant match of heritage and ambition. As one of the UK’s foremost contractors, with a 2022 turnover near £2 billion and experience across high-profile projects, the firm is known for its willingness to tackle architectural challenges that straddle aesthetics, sustainability, and reuse.
Under the contract, Mace will oversee the technical reinvention of the building—improving its energy performance, reconfiguring its internal flow, and adding usable commercial space while retaining the iconic silhouette swirling above the Thames. Early sketches suggest leafy terraces and a more efficient façade that modernises the structure without erasing its identity.
The task ahead is delicate. City Hall’s original design features—particularly the helical ramp—are visually striking but spatially inefficient. For a building whose form once symbolised “transparency” in governance, critics now argue its awkward geometry has made it an impossible knife-edge of architectural performance versus usability. The redevelopment aims to preserve the best of its iconography while making the building economically viable and environmentally fit for purpose.
The context could not be more relevant. London continues to face dual pressure on office real estate—dwindling post-pandemic demand in some areas, coupled with a tight supply of genuinely sustainable, modern workspaces in others. Repurposing rather than demolishing City Hall sends a powerful signal that adaptive reuse can—if done right—deliver both placemaking and pragmatism. It demonstrates that even a polarising architectural landmark can be brought into the 21st century without resting as an empty shell.
Still, questions remain. Will the charm of the ramp survive behind new glass and terraces? How will office tenants fare in a redesigned shell of a civic structure? And, crucially, can developers balance imaginative design with sustainable, profitable return? For Mace, the challenge is clear; for London, the outcome could redefine how iconic—but underused—buildings are reborn.
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