French architect Major Pierre-Charles L’Enfant, hired by President Washington to plan the federal city, selected Capitol Hill—a plateau, actually—as "a pedestal waiting for a monument". Indeed it was. In 1793, George Washington and an entourage of local masons laid the building’s long-lost cornerstone, then celebrated by barbecuing a 500-pound ox. Thirty-one years later, despite a fire, a shortage of funds and the War of 1812, the structure was complete. But as the Union grew, so did the number of legislators. By 1850, architects projected the Capitol would have to double its size. In 1857, they added wings for the Senate (north) and the House of Representatives (south). An iron dome (a 600-gallon paint job each year makes it look like marble) replaced the wooden one in 1865.
Today, as well as being a landmark of neo-classical architecture, the Capitol—which has 540 rooms, 658 windows (108 in the dome alone) and 850 doorways—is something like a small city. As well as the 535 elected lawmakers, an estimated 20,000 workers toil each day among the six buildings (not including the Capitol itself)—all connected by tunnels—that make up the complex. A US flag flies over the Senate and House wings when either is in session; and at night a lantern glows in the Capitol dome.
Tickets for a Capitol tour are free but should be booked online in advance; you’ll be assigned a time (it’s usually possible to secure a slot within a day or two). US citizens can also book through their senator or representative. A limited number of same-day passes are also available from the information desk in Emancipation Hall on the lower level of the Capitol Visitor Center. Entrance to the Capitol is also through the Emancipation Hall. Once inside you will also be able to obtain a pass for the House and Senate floors. More information is available at http://www.visitthecapitol.gov/visit/book_a_tour.
Visits begin with an orientation film, Out of Many, One. The highlight of the short tour is the Rotunda, its dome containing nine million tons of iron. On its ceiling is a massive fresco by Constantino Brumidi, consisting of a portrait of the nation’s first president rising to the heavens flanked by allegorical figures of Liberty and Authority, Victory and Fame. They are surrounded by maidens representing the original 13 colonies. Around the walls are other paintings, with figures depicting elements in American life such as commerce and agriculture; in these scenes mythological gods and goddesses interact with historical figures. The National Statuary Hall was originally the chamber of the House of Representatives, but it outgrew the room, moving to a new chamber, and the room was devoted to statuary. Each state was invited to contribute two statues to honour individuals significant to their state; these are displayed throughout the Capitol and in the visitors’ center.