Washington's third-oldest Federal building, the Treasury, was completed in 1842, after only the White House and the Capitol.
The building holds an unusual distinction: it was placed here in a location that broke the original city plan. Pierre L'Enfant had designed a grand visual axis between the White House and the Capitol down Pennsylvania Avenue. The Treasury Building now sits directly in that sightline, blocking the view. According to popular tradition, President Andrew Jackson, frustrated with debate over where to locate the building, walked out of the White House one day, stabbed his cane into the ground, and said 'put it here.' Whether or not the story is true, the building went here.
The building housed the actual gold and silver reserves of the United States until the Federal Reserve was created in 1913. Secret Service agents were first deployed here — not to guard presidents, but to protect currency and catch counterfeiters. The Secret Service was established as a Treasury Department agency in 1865, the same day Lincoln was shot at Ford's Theatre.
Alexander Hamilton, the first Secretary of the Treasury, faces you from his pedestal on the south side of the building. Hamilton's visage is on the ten-dollar bill, much of which was printed in this building for much of American history.
Look up at the Greek Revival portico and the long sandstone columns. This building predates the Civil War by nearly two decades.