Until the physical gap is filled, the emotional void of 9/11 will continue to haunt the city. Ike Ijeh looks at how designers, architects and builders are working to do justice to the significance of the site. Photography by Keith Kleiner

Only the most callous cynic would have been thinking about construction when the apocalyptic events of 11 September unfolded 10 years ago next week. However, despite, or perhaps because of its grim conception, Ground Zero has become the most famous construction site in the world.

The architectural competition convened in 2002 by the Lower Manhattan Development Corporation (LMDC) to rebuild the World Trade Center and find a replacement for the twin towers was arguably the most hotly contested in history. The winning design by Daniel Libeskind beat entries by some of the world’s most celebrated architects, including Rafael Viñoly and SOM.

Libeskind’s designs became mired in controversy, however, with some, principally World Trade Center leaseholder Larry Silverstein, claiming his proposals were unworkable. Silverstein replaced Libeskind with SOM, which revealed plans in 2005. Ground was broken the following year.

Construction has continued since. To the frustration of many and partially as a result of the legal rows that have blighted the $18bn (£10.5bn) project, completion is not expected until 2015.

As well as the Freedom Tower, which forms the centrepiece of the scheme, the proposals include a masterplan for redeveloping the site. Most of the World Trade Center’s 13.5 million ft2 of office space was destroyed - roughly the size of Canary Wharf. The masterplan intends to restore much of this capacity, as well as incorporate a memorial, public plazas and a transportation hub.

But for all its sheen and glamour, it is unlikely that the architecture of the new World Trade Center will surpass the monolithic solemnity and iconic power of its predecessors. The weight of history will always lend whatever is built reverential status. Moreover, the grip the twin towers have on our emotions is as much a result of the horror of their demise as the strength of their architecture.

Only time will tell whether the new buildings will do justice to the significance of the site. But two things are certain: the completion of the new World Trade Center is essential to provide architectural and symbolic catharsis from the trauma of 11 September. And it will be perhaps the last opportunity to remind the world that despite bigger, brasher versions that have emerged in Asia, the US will always be the spiritual home of the skyscraper.

world trade center

Facade installation has reached the 54th floor of One World Trade Center. WTC7, the only completed tower of the reconstruction, is on the right

WTC 1 (One World Trade Centre/Freedom Tower)

Architect: SOM / Daniel Libeskind
Client: Port Authority of New York and New Jersey
Contractor: Tishman Construction
Structural engineer: WSP Cantor Seinuk
Floors: 104
Area: 2.6 million ft2 (241,548m2)
Height (roof): 1,368ft (417m)
Height (spire): 1,776ft (541m)
Completion date: late 2013
Cost: $3.1bn (£1.8bn)

At 1,776ft high, when the Freedom Tower was initially unveiled in 2002 it was to be the tallest building in the world, proudly aping an accolade the twin towers briefly enjoyed from 1971-73. But the world has moved on since then and One World Trade Center will now have to settle for being the tallest building in the Americas and tallest office only building in the world. However, it remains by far the most scrutinised and high-profile element of the entire WTC reconstruction project. It is also the tower at the most advanced stage of construction and its steel frame already soars 79 storeys up into the Lower Manhattan skyline. It is closely followed by its two concrete cores (70th floor) and glass facade (54th floor).

One World Trade Center is built on the site of the now vanished WTC6, destroyed when the North Tower collapsed on 11 September. It is also roughly equivalent in mass and height to one of the original Minoru Yamasaki-designed twin towers (although its chamfered corners ensure that it provides about a quarter less office space). Like the original South Tower, it will also be surmounted by a public observation deck. This, though, is where the similarity ends. Libeskind’s original design envisaged a spindly, asymmetrical needle that twisted haphazardly up to its summit. Despite the fact it had a chaotic and unresolved quality to it, as if it wasn’t quite sure whether it wanted to be a sculpture or an office block, it did possess a visionary, spiritual resonance that gave form to the symbolic grandeur of the project’s core aspirations.

If one world trade center does somehow become an iconic beacon, it will be solely down to its height and location and not its design

Sadly, little of this remains in SOM’s revised version. A more conventional form has been imposed that tapers octoganally and symmetrically. And in a conceptual snub to the Statue of Liberty and in alleged homage to the Empire State Building, the spire has been centralised. Yet, sprouting superfluously up from a now traditional flat roof, it now seems even more irrelevant than it was in the first scheme.

One World Trade Center will undoubtedly fill the “dip” in New York’s skyline and restore a sleek, confident sense of civic pride and scale back to the city. But if it does one day somehow become the venerated iconic beacon its creators are understandably so desperate to deliver, it will be solely down to its height and location and not its design.


The masterplan for the new World Trade Center features five towers wrapped around the 9/11 memorial

WTC 2 (200 Greenwich Street)

Architect: Foster + Partners
Client: Silverstein Properties
Contractor: Tishman Construction
Structural engineer: WSP Cantor Seinuk
Floors: 78
Area: 2.53 million ft2 (235,000m2)
Height (roof): 1,270ft (387m)
Height (spire): 1,350ft (411m)
Completion date: April 2015
Cost: $2.9bn (£1.7bn)

WTC2 will be the second-tallest building on the World Trade Center site and third tallest in New York City. It will also be the last segment of the masterplan to be completed and will mark the end of the World Trade Center’s reconstruction when it opens in 2015. At present, only sub-grade structural steelwork has been completed and construction is not even expected to reach street level until mid-2012. Libeskind’s masterplan envisaged a belt of towers wrapped around the 11 September memorial and stepping down in height from Freedom Tower, the tallest, to WCT4, the shortest. WCT2 is the second in the sequence.

The tower assumes a cruciform, crystalline form crowned by a diamond-shaped summit, sliced at an angle reverentially to address the memorial below. The building is simply expressed as a cluster of four vertical shafts, the tallest of which is cut away at the top and fitted, superfluously, with an apologetic, tripod-like antenna. As well as office space, it will provide four retail floors and a sky lobby.

The tower is a less radical exploration of high-rise design than Foster’s recent Hearst Tower. But its strident verticality generates a more sinuous form and its distinctive, if rather awkward crown should make a charismatic contribution to the downtown New York skyline.


The new World Trade Center as it is anticipated to look when complete in 2015


WTC 3 (175 Greenwich Street)

Architect: Rogers Stirk Harbour + Partners
Client: Silverstein Properties
Contractor: Tishman Construction
Structural engineer: WSP Cantor Seinuk
Floors: 71
Area: 2.1 million ft2 (195,096m2)
Height (roof): 1,155ft (352m)
Height (spire): 1,240ft (378m)
Completion date: 2014
Cost: $2.75bn (£1.6bn)

The middle tower of the trio of skyscrapers that will flank the eastern side of the memorial will be the fourth tallest in New York City when complete. Like WTC2, construction is at an early stage and sub-grade steel superstructure works only began in April. The tower is a typical example of the structural expressionism and modular assembly that drives RSHP’s work. The tower is actually a group of three extruded and articulated vertical shafts with a projecting podium block containing retail and public areas as well as trading floors.

The varying height of each element creates a stepped profile, which again doubles as a massing metaphor that defers to the smaller scale of the memorial below. The central shaft is treated as the boldest architectural segment with exposed structural cross-bracing extending up its full height and four pinnacles mounted on each corner. The tower casts a mechanised and strongly orthogonal presence onto the site, although the casual observer may spot that RSHP has raided the same increasingly familiar kit of parts deployed on several of its other
high-rise schemes across the world.

WTC 4 (150 Greenwich Street)

Architect: Maki and Associates
Client: Silverstein Properties
Contractor: Tishman Construction
Structural engineer: Leslie E. Roberston Associates
Floors: 61
Area: 1.8 million ft2 (167,000m2)
Height: 947ft (297m)
Completion date: 2013

The shortest of the new WTC skyscrapers will be the only tower on the site shorter than the Shard, Europe’s tallest building. After WTC1, it is also the building that has reached the most advanced stage of completion. Steelwork has now advanced to the 37th floor, concrete pouring has reached the 30th and curtain wall installation has begun. In massing terms, the building negotiates the final shift in scale from the high-rise scale of the skyscrapers to the human scale of the memorial. Therefore, the top third of the tower is diagonally cut back from its lower face to create a final “step” down to the memorial.

The building is clad simply in sheer curtain walls of reflective glazing providing a sleek, honed finish. A projecting five-storey glass podium contains retail spaces and provides animated street-level interaction. Throughout, the tower’s minimalist, understated design reflects its conceptual position within the massing hierarchy of the four new WTC towers. Yet this restraint bestows a quiet dignity that forms one of the most subtle and poignant architectural eulogies on the World Trade Center site.

WTC 5 (130 Liberty Street)

Kohn Pedersen Fox had prepared plans for a 40-storey, 743ft tower for JP Morgan Chase to replace the former Deutsche Bank Building heavily damaged during the attacks. Designated as a residential tower in the original masterplan, KPF’s commercial re-working involved a 12th floor, seven-storey cantilevered projection over the adjacent rebuilt St Nicholas Church.However, plans are now indefinitely on hold for the tower following JP Morgan’s relocation to another Manhattan site.

new york

WTC 7 (250 Greenwich Street)

Architect: SOM
Client: Silverstein Properties
Contractor: Tishman Construction
Structural engineer: WSP Cantor Seinuk
Floors: 52
Area: 1.7 million ft2 (158,000m2)
Height: 741ft (226m)
Completion date: 2006

WTC7 is the only building on the World Trade Centre complex that has been completed. As it is also the only other tower on the site designed by SOM, it provides a tantalising glimpse of the design characteristics Freedom Tower itself may eventually assume and of what the entire complex may look like when finally complete. The original red granite-faced WTC7 was completed in 1987 by Emery Roth & Sons, consultant architect on the twin towers. It was the only other tower apart from the twin towers to collapse on 11 September - albeit over six hours after the attacks began, a timeframe responsible for some of the more idiotic conspiracy theories ignited by the day’s events. Construction began on its replacement as early as 2002 and it was completed in 2006. Two factors explain the speed of its reconstruction in comparison to the rest of the site. The first 10 storeys house a sub-station that powers most of Lower Manhattan and the building is located just outside the WTC property boundary and therefore subject to a much less stringent set of bureaucratic approvals.

The new WTC7 tower oozes all the slick and stylised corporate panache that SOM is so adept at delivering. Razor-sharp edged and uniformly clad in a shimmering curtain wall, its glazing comprises panels of low iron, ultra-clear glass for maximum light and reflectivity. The simple, linear subdivision of its facades into frames of stainless steel spandrels interspersed with dominant horizontal channels recalls both the Miesian tradition that informed the twin towers and the fifties international style that was so influential on New York skyscrapers. This is functional, no-nonsense modernist US high-rise design, an unadorned glass box free of all the funny spikes, pinnacles and incisions found elsewhere on the site. Vertical, staggered stainless steel louvres encase the 10-storey sub-station base and morph into an ethereally illuminated opaque blue veil at night. The New York Academy of Sciences is located on the 40th floor.  

WTC Transportation Hub

Architect: Santiago Calatrava
Client/Contractor: The Port Authority of New York and New Jersey
Area (station): 800,000ft2 (74,3222m2)
Area (retail): 500,000ft2 (46,451m2)
Completion date: mid-2014
Cost: $3.44bn (£2bn)

After the memorial and museum, the new PATH (Port Authority Trans-Hudson) terminal at the WTC site arguably harbours the strongest spiritual aspirations. Calatrava has compared the building to a “bird being released from a child’s hand”. With twin 150ft winged canopies thrusting skywards from a ribbed steel and glass cage, its soaring form resembles the kind of zoomorphic allegory that is the hallmark of Calatrava’s architecture. Its curves and asymmetry also mark a welcome break from the angular rigidity that characterises the rest of the development. At present, 225 of the 300 steel components that comprise the roof of the underground concourse have been installed. Also, sections of the 271-ton Vierendeel Truss that will serve as a mezzanine roof have also been laid. (The Vierendeel Truss is the same structural format as employed on the twin towers.)

However, the hub has not been without its own share of controversy. Libeskind’s original masterplan envisaged a smaller underground station, similar to its predecessor. Its larger incarnation allegedly provoked the ire of Silverstein, irked by the loss of commercial space. It is also situated on a site that Libeskind had kept open for his Wedge of Light, a sunlight axis that aims to prevent shadows being cast on the memorial on 11 September each year. Furthermore, its budget has ballooned from $2.2bn, and two years ago the client parted company with the original contractor (Phoenix, a consortium that included Bovis Lend Lease and Skanska) to manage construction itself. Finally, some design elements have been watered down due to security and cost concerns. Additional ribs have appeared, the canopies have lost their glazing and the opening roof mechanism has been scrapped.

Nevertheless, when complete, lower Manhattan should still have a transport terminal to rival Grand Central Station for the first time. About 250,000 commuters are set to use it every day and they will be met with what is arguably the most spectacular and visionary piece of architecture at the World Trade Center site.

ground zero

Memorial Plaza, featuring the Memorial Museum (top left) and the two 60m x 60m pools of the Memorial, is scheduled to open next Sunday on the 10th anniversary of the attacks

National September 11 Memorial and Museum

Architect (museum): Aedas
Architect (memorial): Michael Arad and Peter Walker
Client/contractor: The Port Authority of New York and New Jersey
Structural engineer: WSP Cantor Seinuk
Completion date: mid-2013
Cost: $530m (£311m)

Memorial Plaza, the public space that at the centre of the World Trade Center site, is due formally to open next Sunday on the 10th anniversary of the attacks. The 8-acre square features lines of 300 trees interrupted by two giant reflecting pools. The National Memorial Museum to 11 September is also located in the plaza and although it is not scheduled to open until 2013, structural steel and facade installation is now complete. The pools, known as Reflecting Absence, form the National Memorial. The winning scheme was selected in 2004 from more than 5,000 entries. Each pool is located at the bottom of a 9m-deep void and is situated where the towers once stood. Their footprints, 60m x 60m, also match those of the towers. A water fountain runs down the edge of each void and the names of the people who died during the attacks are inscribed along the edges. The memorial will be a powerful reminder of the loss and hope symbolised by the World Trade Center’s slow but inevitable rebirth.