Extending along the eastern end of the Mall, the labyrinthine Capitol building, with its cast-iron dome topped by the statue of Freedom, is the city's most prominent landmark. This massive symbol of democracy in progress has housed the US Congress since 1800. You may visit the building by guided tour only (advance reservations are a must); tours begin in the Capitol Visitor Center and pass through the Rotunda and the Exhibition Hall. You can also acquire passes to the galleries above the House and Senate chambers to view the legislative bodies when they are in session.