1 Undershaft

1 Undershaft is one of the most ambitious and technically demanding demolition and redevelopment projects in the City of London.

On behalf of Stanhope, Keltbray is delivering the dismantling of a 118‑metre commercial high‑rise, marking the largest tower demolition ever undertaken in the Square Mile.

The building’s unusual top‑hung structure creates a genuine demolition challenge. Working with Wentworth, Keltbray is applying an integrated services approach, including asbestos removal, soft strip, temporary works, tower crane installation and structural demolition, to safely dismantle the building ahead of the site’s future redevelopment as One London.

Key Facts

• Managing a top‑hung structure: The building required a bespoke approach due to its rare top‑hung design. Keltbray is installing steel props floor by floor to safely transfer loads before removing the upper trusses, effectively turning the external shell into the building’s new structural spine. More than 700 tonnes of steel support the controlled top‑down demolition.
• Delivering in a constrained city centre: Working in the heart of the Square Mile demands precise logistics. Limited space for storage is managed through phased delivery, strict traffic controls and close coordination with neighbouring developments to maintain progress while minimising disruption.
• Integrated specialist services: Asbestos removal, soft strip, temporary works, tower crane installation and structural demolition are delivered through a coordinated, multidisciplinary approach, ensuring safety, efficiency and