By John T. Marck

Interestingly, the Treasury Department Building, as we see it today, took 33 years to complete, from 1836 to 1869. Robert Mills, an architect who designed the Washington Monument and the Patent Office Building, designed the east and center wings of the Treasury Building. This first part of the structure was built between 1836 and 1842.

The most impressive design from Mills is the east colonnade that runs the entire length of the building. Each of the 309 columns is 36 feet in height and is carved from a single piece of granite.

In later years, additions were made to the buildings original wings, starting with the construction of the south wing from 1855 to 1860, and the west wing from 1855 to 1864. The design of these wings was done by Thomas Ustick Walter, architect of the Capitol dome; however, architects Ammi B. Young and Isaiah Rogers refined his plans, designed the interior and supervised the construction. In the interior, iron columns and beams were used to reinforce the building brick vaults. The final addition was the north wing, built from 1867 to 1869. Its architect was Alfred B. Mullett and is similar in construction and décor to the south and west wings. The north wing is unique in that it contains the cash room, and a two-story marble hall in which the daily financial business of the US government was transacted. The room opened in 1869 and was the site of President Grant’s inaugural reception.

The Treasury Department Building is the oldest departmental building in Washington, and because it was here first, had a great impact and influence of subsequent designs of buildings that followed. When it was finally completed in 1869, it was one of the largest office buildings in the world. During the Civil War, it served as barracks for Union soldiers and was the temporary White House for President Andrew Johnson following the assassination of President Lincoln in 1865. The building was declared a National Historic Landmark in 1972.