Since then, a surprising number of similar buildings have sprouted or been proposed around the world, many designed by Cesar Pelli as an evolution of Cira Centre itself. Madrid's Torre de Cristal, standing at 819 feet, is the results of Pelli's further experimentation with Philadelphia's Cira Centre which stands about 400 feet shorter.
Proposed at 30th between Chestnut and Walnut is Cira Centre South, in which Pelli expands his geode across Market, lining the west bank of the Schuylkill River.
Cira Centre SouthWilmington even got in on the action, proposing Two Christina Centre.
As Cesar Pelli expanded upon his concept, firms worldwide began implementing this asymmetrical design in denser downtown areas. Cook + Fox Architects' Bank of America Tower in New York (which has topped our Comcast Center as the nation's tallest green building only because of its erection) was completed in 2009.
Downtown Los Angeles' renaissance has drawn proposals from two firms. A. C. Martin's Wilshire Grand Hotel looks like an elongated Bank of America Tower, while Richard Keating's Maguire Office Tower looks suspiciously identical to Cesar Pelli's Cira Centre South.