Council on Tall Buildings and Urban Habitat
The Willis Building (51 Lime Street), London
Featured September 2014
51 Lime Street was recognized as the "Best Tall Building Europe" in the 2008 CTBUH Awards Program.
Other Featured Tall Buildings

“This is a project that integrates well with the urban context, both historic and modern.  I appreciate its sensitivity to the environment through the building’s ‘serrated’ exterior that simultaneously shades from the sun while letting views out.”
- Tim Johnson,
CTBUH 2008 Awards Chair, NBBJ

125 m (409 ft)
Primary Use

The British Land Co/ Stanhope/ St. Martins Property Group
Design Architect
Foster + Partners

Structural Engineer
Ramboll Whitbybird
MEP Engineer
Roger Preston and Partners

Mace Ltd.

Europe is not known for very tall structures.  This is largely due to significant historic fabrics developed over typically many centuries and the protection and respect needed for these areas.  What the jury found most interesting in 51 Lime Street is that it is a project that integrates well with the urban context, both historic and modern.  The project establishes a great dialogue with the existing fabric of historic masonry buildings and more modern glass   buildings.  The building accomplishes this though its dramatic form, its materiality, and by the articulation of the massing. The jury appreciated the design team’s sensitivity to the environment.  The building’s “serrated” exterior simultaneously shades the façade from the sun and allows views out to the city.  In addition, the formation of public gathering spaces and resulting activation of the ground plane further reinforces the CTBUH mission to see tall buildings integrated into the urban environment.

Figure 1. View from the north

51 Lime Street acknowledges that the way in which an office building responds to the context and spirit of the city in which it stands is as fundamental to its success as the acknowledged benefits of natural ventilation, light, open space and a view. As a result, the architects continue their built explorations into new strategies for flexible, column-free office space, but have also created the idea of the “urban room”, where genuine connections to the public realm are established, and the way in which the building “touches” the ground is paramount.

Figure 2. Ground level plaza
Figure 3. Top of glass curtain walls
51 Lime Street, also called the Willis Building (after its primary tenant), sits in the heart of the City of London. It lies to the east of Richard Rogers’ 1986 Lloyds Building and responds to this unique location with an elegant concave form. The project is significant in both urban and environmental terms—51 Lime Street is among a number of projects in the City of London that have struck a delicate balance between commercial requirements, the need for flexibility, and respect for the area’s world-famous architectural heritage. The original building for Willis Faber Dumas by Foster + Partners in 1976 was a seminal project for the practice, an open office building characterized by its sense of community —this spirit has been kept alive in the new UK headquarters in London, with expansive roof terraces that offer broad views over the city.
Figure 4. Looking down at the rooftop terrace
The development comprises two separate buildings which step down to a new public plaza. The 10-story building at 1 Fenchurch Street responds to the smaller scale of Billiter Street and Fenchurch Avenue, while the 29-story Willis headquarters building rises to the west of the site. The smaller building’s concave façade encircles the plaza and its curved corners maintain important view corridors, and also restore a pedestrian route through the site, reinforcing the medieval street pattern. The landscaping also features sculpture reclaimed from the previous building, linear benches and a living wall to replace the existing ‘party wall’ between the Willis Building and its neighbors, improving the view from the building and encouraging biodiversity. With a fringe of cafes, restaurants, shops and bars at the tower’s base, 51 Lime Street extends the vibrancy of the nearby Leadenhall Market, a particularly lively shopping area in the City with a strong architectural character.
Figure 5. With The Lloyd's Building and 30 St. Mary Axe
Figure 6. Main Elevator lobby
As towers grow ever taller, the strategies to achieve stability are increasingly central to the design approach. On plan, the Willis headquarters has been developed as a series of overlapping curved shells, while its section is arranged in three steps. The roof terraces overlooking the plaza on the lower two steps are directly accessible from the office spaces. Both buildings have a central core to provide open floor plates and maximum flexibility in use, so they are able to accommodate a number of different configurations for one or more tenants.
Figure 7. The “saw toothed” facade reduces solar gain and glare
The entire development is visually unified by its highly reflective façade. The pressed form of the panels and their mica finish give them depth and texture. A strong language is established through the interplay of solid and glazed panels arranged in a saw-tooth pattern. The fins also increase insulation while reducing glare and solar gain—just one of the strategies that have contributed to the building’s BREEAM “excellent” rating. Together with highly efficient services equipment and systems and extensive bicycle parking, the building’s progressive environmental strategy surpasses statutory carbon reduction targets by more than 20%.

Related Links
CTBUH Skyscraper Center Profile:
51 Lime Street

51 Lime Street was recognized as the Best Tall Building Europe in the 2008 CTBUH Awards Program.
Download 51 Lime Street 2008 CTBUH Awards Book section

2008 CTBUH Awards Book

The CTBUH would like to thank Foster + Partners for their assistance with this article.
Photography © Nigel Young/Foster + Partners