Built at a time of diplomatic tensions with the United Kingdom in the late s, known as the Caroline Affair, the barracks were named for Joel Robert Poinsett, Secretary of War under Martin Van Buren, and former Ambassador to Mexico, whom introduced the Poinsettia to the United States in the s. Poinsett had visited Buffalo during the Caroline Affair and, as a result, the new barracks were named in his honor.
In , construction began on the more strategically positioned Fort Porter, which stood on the site of the present-day eastern landing of the Peace Bridge along the Niagara River, with the base being completed by and the Poinsett Barracks being subdivided and absorbed into the growing city of Buffalo, with Franklin Street and Pearl Street being run through the middle of the site.
This is the only surviving building from the former military post. In , the house was purchased by Dexter Rumsey and given as a wedding present to his daughter, Mary Grace Wilcox, upon her marriage to lawyer Ansley Wilcox, with the Wilcox family owning and inhabiting the house from until Ansley Wilcox was a close friend and political ally of Theodore Roosevelt, having met while working on a special commission on civil service reform under then-New York Governor Grover Cleveland in the s, and both men having pushed to create the Niagara Reservation, now Niagara Falls State Park, in The inauguration was attended by 50 people, including cabinet officials, dignitaries, and family members, as well as the Wilcox family.
Pinckney in , and former Governor of Idaho Frank Steunenberg in , as well as an attempted assassination of Theodore Roosevelt himself in In , the carriage house, demolished in , was rebuilt as a visitor center for the museum, and the adjacent bank building constructed in was demolished to restore the south lawn of the house in The house features a painted brick exterior, front gable roof with a two-story ionic portico on the symmetrical five-bay west facade, six-over-six double-hung windows, a palladian attic window on the pediment above the portico, side gables that once formed the ends of the front wing of the house, which was originally a duplex, with corinthian pilasters at the corners of the protruding wing to the south, an oriel window on the first floor of the south facade, a brick east wing built in with a rear gable roof and an asymmetrical rear facade, an enclosed portico on the north facade, and a rooftop widows walk atop the roof of the original section of the house.
To the north of the house is a carriage house, rebuilt in , which features a painted brick exterior, hipped roof with gabled wall dormers to the north and south and a cupola atop the center of the roof, and a glass vestibule connecting to the rear wing of the adjacent house.
