Assay Office, pre-1916.

In 1822 the Verplanck family sold the land on which their mid-18th century mansion sat for $40,000 (quite a sum for the time) to the Bank of the United States. On the site the institution constructed the Branch Bank of the United States, a two-story classical structure rendered in white marble. Designed by Martin E. Thompson, the bank building, completed in 1823, looked less like a bank and more like an English country estate. The bank lost its charter in 1836, got a new one, but closed the following year in the midst of a financial crash.

Later used by the equally descriptively named Bank of the State of New York, the building was sold to the government in 1853 for use as an Assay Office. Here gold and other precious metals (including those coming out of the California Gold Rush) would be tested for purity before being sold. The building was also the location where the metals were melted down into bars and stamped with their weight and quality.

The building operated as the United States Assay Office for more than 50 years, but the deterioration of the nearly 100 years old edifice was transparent at the start of the 20th century and the building was largely abandoned by 1911. Proposals to save the building included moving it elsewhere or attaching the new Assay Office to the old facade, while what actually occurred was a curious mix of both these ideas. In 1915, the government presented the facade to the Metropolitan Museum of Art. After being deconstructed and catalogued, it was re-installed (seven years later) stone by stone in the new American Wing.