Alfred B. Mullett was born in England in 1834. His family immigrated to Glendale, Ohio in 1845. A couple of years later he began work in the Cincinnati office of architect Isaiah Rogers.

Mullett later moved to Washington, D.C. and in 1863 began work for the Treasury Department. He rose to the position of Supervising Architect in 1866.

During his eight years as Supervising Architect, he oversaw the design and construction of over forty federal buildings across America.

Several of these buildings are still standing, including the Mint in Carson City, NV, the Mint in San Francisco, CA, and the State, War and Navy Building (now the Old Executive Office Building) in Washington, D.C.