The Chicago Spire is a skyscraper under construction in the U.S. city of Chicago, Illinois. Construction work began in 2007 but was put on hold in 2008 before any of the superstructure had been built. The building was designed by Spanish architect Santiago Calatrava and is being developed by Garrett Kelleher of Shelbourne Development Group, Inc. If completed, at 2,000 feet (610 m) and with 150 floors, it will be among the world's tallest buildings and freestanding structures.
Originally announced in May 2005 by Christopher T. Carley of the Fordham Company, the project was supported by many Chicagoans and city officials. After several months of development, Carley failed to acquire necessary financing and the project was taken over by Garrett Kelleher of the Shelbourne Development Group. Since that time, three major revisions were made to the design. Construction of the Chicago Spire has stopped and will not resume until the markets improve from the subprime mortgage crisis. On October 8, 2008, Santiago Calatrava filed a lien on the project stating that the developer has yet to pay him the $11.34 million owed for his work, casting some doubt over the future of the project.
Originally proposed as the Fordham Spire in July 2005, the design called for 115 stories. Chicago developer Christopher T. Carley of the Fordham Company was spearheading the project. The building was planned to include a hotel and condominiums and also featured a tall broadcast antenna mast. On March 16, 2006, the initial design of the building passed unanimously during that day's meeting of the Chicago Plan Commission and on March 23, 2006, the same happened at the city's Zoning Committee meeting. On March 29, 2006, The Chicago City Council also approved that design. As part of the approval process, the council passed a measure that raised the height limit on structures at the site to accommodate the 2,000-foot (610 m) tower.
There was widespread support for the original design of the building among both the residents of the immediate neighborhood and the city of Chicago as a whole, partly because the building would block less sunlight and obscure less of the skyline than would the uses for which the land was originally zoned. Chicago Mayor Daley said he approved of the design, stating that it was environmentally friendly. Chicago's 42nd Ward Alderman Burton F. Natarus, who was the local ward alderman when the building was announced, said: "This is a very unique opportunity for the city of Chicago. This building belongs to Chicago and should be in Chicago."
Opposition from some neighborhood residents originated from concerns with increased congestion. Donald Trump immediately voiced opposition to the building, stating that the structure would be a target for terrorists and did not even seem to be a viable project. One of his projects, however, the Trump International Hotel and Tower, is also a skyscraper that completed construction in January 2009 just a few blocks west of the Chicago Spire site; the building would be displaced by the Chicago Spire as the tallest residential structure in the United States, and would also be in direct competition with the tower in selling residential units.
As with many of his designs, Calatrava has been inspired by themes and designs in nature for the tall, twisting skyscraper. For the design of the building, he likened the structure to an imaginary smoke spiral coming from a campfire near the Chicago River lit by Native Americans indigenous to the area, and also related the building's newly designed pinnacle to the "graceful" and "rotating forms" of a snail shell.
Standing at 2,000 feet (610 m), the Chicago Spire would further transform the always-changing Chicago skyline. Plans for the tower include 1,193 condominiums with each of the building's 150 stories rotating 2.4 degrees from the one below for a total 360 degree rotation. In February 2008, prices for the condominiums were announced as ranging from $750,000 to $40 million USD. For supplemental structural support, each floor would be surrounded by cantilevered corners and four concave sides. Similar to the Willis (formerly Sears) Tower and John Hancock Center observation decks, the Chicago Spire will house a community room at the top floor offering residents a view of four states. The soaring four story lobby of the skyscraper will have translucent glass walls and be framed by arching, steel reinforced concrete vaults. The building has been labeled as a giant "drill bit" by the public and others in the media have likened it to a "tall twisting tree" and a "blade of grass".
The curved design, similar to that of Calatrava's Turning Torso in Malmö, Sweden, may provide two major benefits to the structure of the building. First, curved designs have a tendency of adding to the strength of a structure. A similar principle has been applied in the past with curved stadium roofs. In addition to structural support, the curved face of the exterior will minimize wind forces. In rectangular buildings, a fluid wind flow puts pressure on the windward face of the building; while air moves around it, a suction is applied to the leeward face. This often causes a sway in tall buildings which can be counteracted, at least partially, by stiffening the structure or by using a dynamic wind damper. Although the curved design of the Chicago Spire will not completely negate wind forces, a tapering concrete core and twelve shear walls emanating from it are installed to counteract these forces instead.
Additionally, the Chicago Spire will incorporate world-class sustainable engineering practices to meet Leadership in Energy and Environmental Design Gold recognition. Sustainable features include recycled rainwater, river water used for cooling, ornithologically-sensitive glass to protect migratory birds, intelligent building and management systems, waste storage and recycling management, and monitored outdoor air delivery.