Pennsylvania Avenue and U.S. Capitol. 19th century stereoscopic views of Pennsylvania.

The original U.S. Capitol building, known as the "Old Capitol," was a small brick building that was completed in 1800. It served as the Capitol building until the current building was completed in the 1850s. The current building, which is made of white marble and granite, was designed by architect William Thornton and later modified by architect Thomas U. Walter.

Construction of the current U.S. Capitol building began in 1793 but was interrupted several times by war and lack of funds. The building was completed in the 1850s, but the dome was not finished until after the Civil War in the 1860s.

Now, the U.S. Capitol is the home of the United States Congress and the seat of the legislative branch of the federal government. It is located in Washington, D.C., and is one of the most iconic buildings in the United States.