The Treasury Building took 33 years to build from 1836 – 1869. It was primarily designed by the same man, Robert Mills, who was the architect of the Washington Monument. At the time of its construction, the Treasury Building was one of the largest office buildings in the world. It served as a barracks during the Civil War and a temporary White House for President Andrew Johnson after President Lincoln’s assassination. Built in the Greek Revival style, Treasury was the first Departmental building in the nation’s capital thus influencing the design of many of the others.