John Kellum

Kellum, born in Hempstead, Long Island, was trained as a carpenter; he was largely self-taught in architecture, and was taken into partnership in 1846 by the well-established New York architect Gamaliel King.

King was engaged in constructing Brooklyn City Hall, and Kellum, as junior partner, was his on-site supervisor.

Kellum designed and built for Stewart the Working Women's Hotel (1869–75, demolished), on Park Avenue between 32nd and 33rd Streets.

Kellum was also the primary architect[6] of the New York County Courthouse (1861 onwards; completed with revised and elaborated interiors, 1881), on Chambers Street behind New York City Hall; it is known as the "Tweed Courthouse" after William Marcy "Boss" Tweed, who commissioned it and profited from kickbacks during its construction.

Kellum's exterior is in the Italianate manner; immense cast-iron structural and decorative elements are to be seen in the public spaces of the rich interiors.

Kellum's A. T. Stewart residence, 34th Street and Fifth Avenue.
For A.T. Stewart Kellum's cast-iron "Palace", (1859-62), occupied a full block at Broadway and 10th St.