Gilbert is known for designing the first steel-framed curtain wall building in New York, the Tower Building, which opened at 50 Broadway in 1889. The Tower Building is considered New York City's first skyscraper. There is some dispute as to whether the Tower Building had eleven or thirteen floors, depending on which floors were counted and which side of the building was considered. It had to have the steel-frame construction because on its narrow lot, masonry-supporting walls would have allowed almost no free space on the first floor. Gilbert's design used the same frame as a railroad bridge, but rotated vertically.
The Tower Building was initially greeted with great skepticism, with members of the public predicting it would blow over. This prompted Gilbert to scale the building in the middle of an 1889 hurricane to demonstrate with a plumb line that the building was not vibrating. The building was razed in 1914.
Most of his New York buildings have been demolished, but his landmark eleven story Flatiron Building (1898) still stands in Atlanta, Georgia, and predates the similar and more famous New York City Flatiron Building by five years.
Gilbert was also heavily involved in the work of Jerry McAuley, noted missionary at the Water Street Rescue Mission in New York and continued to support the mission after McAuley's death in 1884. Gilbert was first married in 1871 in New York to Cora, daughter of Captain John Rathbone.
After his divorce, Gilbert wed Maria (Fahy) McAuley, widow of Jerry McAuley in 1892 in Cranford, New Jersey. On February 12, 1896, Bradford and Maria had a daughter, Blossom.
^ abEdward Robb Ellis (1997). The Epic of New York. pp. 407–08.
^ abDenenberg, Barry (September 1, 2010). "Skyscrapers". Magical Hystory Tour: The Origins of the Commonplace & Curious in America. Archived from the original on June 29, 2015. Retrieved August 16, 2011.
^Landau, Sarah Bradford and Condit Carl W. Condit (1996). Rise of the New York Skyscrapers 1865-1913. Yale University Press. pp. 161–66, 416.
^Gilbert, Sketch Portfolio of Railroad Stations (The Railroad Gazette, 1885). The book notes that his work on railroad architecture was the subject of a special exhibit at the World's Columbian Exposition (the Chicago World's Fair) in 1893, for which he received a special medal.
^Fletcher, Katharine (2004). Capital Walks: Walking Tours of Ottawa. Fitzhenry & Whiteside, Markham, Ontario. Page 73.