 Part of the delay was caused by the slowness of the city authorities to authorize metal-frame construction techniques; it was not until 1889 that they relented and allowed Bradford Gilbert to construct the Tower Building, an 11-story iron-framed skyscraper.This encouraged the building of more skyscrapers in New York, although the city remained cautious about the technology for some years.Finally, in 1895 a breakthrough was made with the construction of the American Surety Building, a twenty-story, high-steel development that broke Chicago's height record.