1 Undershaft

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1 Undershaft
Proposed design of 1 Undershaft, London.jpg
Proposed design for 1 Undershaft (centre), standing to the left of The Gherkin
General information
Address1 Undershaft
Town or cityLondon, EC3
CountryUnited Kingdom
ClientAroland Holdings
Architectural300 m (984 ft)
Technical details
Floor count74
Floor area132,000 m2 (1,420,836 sq ft) (office)[1]
Design and construction
Architecture firmEric Parry Architects
Structural engineerWSP[2]

Coordinates: 51°30′51″N 0°04′54″W / 51.514242°N 0.081583°W / 51.514242; -0.081583

1 Undershaft, informally known as The Trellis due to its external cross bracing, is a skyscraper planned for the City of London financial district which was given approval in November 2016. The scheme has been developed by Aroland Holdings and designed by Eric Parry Architects. It is set replace the St Helen's tower and upon completion will become the second tallest skyscraper in London and the United Kingdom.

The building is the second design for a skyscraper at 1 Undershaft, replacing a previous proposal designed by architects Avery Associates. The approved plans are also revised, reducing the height of the tower. Construction may not begin until several years after its approval date.


Original proposal[edit]

Original design by Avery Associates, to the immediate right of 122 Leadenhall Street

In January 2015, early plans emerged of a replacement office building for the St Helen's tower in Undershaft within London's Square Mile.[3] The proposal, named 1 Undershaft, was designed by Avery Associates who began working on the scheme in collaboration with the then owner of the site Simon Halabi in 2010.[4] At 270 metres (885 ft), it would have become the third tallest building in London and the United Kingdom behind The Shard and the stalled Bishopsgate Tower.[5]

New proposal[edit]

In July 2015, details of a revised scheme by the new owners of the site, Aroland Holdings, were reported. The plans were for a skyscraper of 304 m (997 ft) designed by Eric Parry Architects.[6] According to some reports, the design could be "modelled on Cleopatra's Needle".[7]

In December 2015, the new design was released for a tower of 294.6 metres (966.5 ft) with 73 floors.[8][9] Subject to planning permission, it was set to become the tallest building in the Square Mile when completed and the second tallest building in London and the United Kingdom behind The Shard.[5] A consultation process took place in autumn 2015.[10] On 8 February 2016, a planning application was submitted for the development,[11] with a decision expected to be made in September 2016.[12]

However, a revised planning application was submitted by the developer which reduced the proposed height by 4.66 m to 289.9 m (951.2 ft), due to possible interference with the flight paths of the nearby London City Airport. Each floor has been reduced in height by 50 mm and structural floor beam depths have been changed. In addition, the level of the soffit has been decreased and the viewing gallery height has been reduced, which was intended to be double height. Despite its height reduction, the proposed height will still make 1 Undershaft the second tallest building in London and the United Kingdom upon completion.[13]

1 Undershaft would replace the St Helen's tower, pictured above

Following a recommendation by planning officers for approval, the scheme was approved by the City of London Corporation on 28 November 2016, with 19 votes in support and two against and given final approval by Mayor of London Sadiq Khan on 12 December 2016.[14][15][16] The start date for construction of the scheme has not yet been decided, but building work is expected to be finished anywhere between six and ten years from its approval date,[17] with demolition of the St Helen's building currently on the site expected to take 18 months and construction of 1 Undershaft due to take between three and four years.[18]


The proposed skyscraper is rectangular in shape and slightly tapers as it gets higher.[19] Developer Aroland Holdings originally wanted 1 Undershaft to be taller than the proposed height. However, the height has been limited by the Civil Aviation Authority (CAA) to avoid intruding on flight paths. In addition, the building's crown, which was intended to resemble Cleopatra's Needle, was not accepted by City planners who wanted "a less demonstrative top. They didn’t want another overt shape".[19]

The tower is designed to be built 10.5 metres off the ground in order to create public space underneath the building. To make room for the public space, the core will need to be positioned to the side of the tower. As a result, bronze diamond shaped external cross bracing will be required, giving the building its nickname The Trellis.[8][20][21]

A public square is also part of the proposed scheme with 2,178 m2 (23,444 sq ft) of retail space below ground level.[1][19] The top of the skyscraper is set to have London's highest viewing gallery free for public access (which could include a museum run by Museum of London),[22] and a restaurant.[8][19]

See also[edit]


  1. ^ a b Waite, Braidwood, Richard, Ella. "Thumbs up for tallest tower in City". Architects Journal. Retrieved 29 November 2016.
  2. ^ Rogers, Dave. "Singapore developer unveils plans for London's tallest tower". Building. Retrieved 24 October 2016.
  3. ^ "Construction Enquirer » Design unveiled for City of London's tallest skyscraper". constructionenquirer.com. Archived from the original on 2015-03-25. Retrieved 2015-01-21.
  4. ^ "Avery Associates Reveals Design for 270-Metre Tower Next to London's Cheesegrater". ArchDaily. Archived from the original on 2015-03-25. Retrieved 2015-01-21.
  5. ^ a b "Skyscraper Center - London". skyscrapercenter.com. Retrieved 8 October 2015.
  6. ^ "Plans for skyscraper to rival the Shard to be submitted to City of London". Standard.co.uk. Retrieved 10 July 2015.
  7. ^ "22 Bishopsgate – and the steroidal towers set to ruin London's skyline". theguardian.com. Retrieved 12 July 2015.
  8. ^ a b c "Eric Parry Architects unveils tallest tower in City of London". dezeen.com. Retrieved 7 December 2015.
  9. ^ "No.1 Undershaft at The Skyscraper Center". skyscrapercenter.com. Retrieved 7 December 2015.
  10. ^ "Plans for skyscraper to rival the Shard to be submitted to City of London". Standard.co.uk. Retrieved 12 July 2015.
  11. ^ Williams, Richard. "Plans for City of London's tallest building submitted". propertyweek.com. Archived from the original on 9 February 2016. Retrieved 9 February 2016.
  12. ^ Bevan, Robert (21 July 2016). "The Shaft will rival the The Shard for coolest skyscraper in London". standard.co.uk. Retrieved 23 July 2016.
  13. ^ Waite, Richard. "Eric Parry reduces height of tallest tower in City". architectsjournal.co.uk. Retrieved 3 October 2016.
  14. ^ Lynch, Russell (21 November 2016). "Square Mile's tallest tower dubbed the "Trellis", set for thumbs-up". Evening Standard. Retrieved 21 November 2016.
  15. ^ Bourke, Joanna (28 November 2016). "Plans to build City of London's tallest skyscraper given green light". Evening Standard. Retrieved 28 November 2016.
  16. ^ Prynn, Jonathan (13 December 2016). "Sadiq Khan gives backing for City's two tallest towers to be built". Evening Standard. Retrieved 27 April 2017.
  17. ^ Sullivan, Connor. "Subscribe to read". www.ft.com. Retrieved 28 November 2016.
  18. ^ Bury, Rhiannon. "1 Undershaft, the tallest tower in the City of London, gets the green light". The Telegraph. Retrieved 28 November 2016.
  19. ^ a b c d Wainwright, Oliver. "1 Undershaft, the tallest skyscraper in the City of London, revealed". Guardian.com. Retrieved 7 December 2015.
  20. ^ Heathcote, Edwin. "City of London's tallest building rises above corporate interests". ft.com. Retrieved 7 December 2015.
  21. ^ Morby, Aaron. "London's second tallest tower set for approval | Construction Enquirer". www.constructionenquirer.com. Retrieved 28 November 2016.
  22. ^ Haslett, Emma (2 June 2016). "Could a new City skyscraper host London's highest museum?". cityam.com. Retrieved 24 November 2016.

External links[edit]