The United States Capitol is one of the most iconic and aesthetically significant structures in the country. For almost two centuries, it has held the meeting rooms of the House of Representatives and the Senate. The Capitol, which began construction in 1793, has gone through several phases. The current building was designed by American architect Henry Hobson Richardson and completed in 1855. Its neoclassical design features large blocks of white Vermont marble and an imposing bronze statue of George Washington on his horse, Liberty. The interior of the Capitol is decorated with paintings by American artists including John James Audubon, Gilbert Stuart, and Emanuel Leutze. The Capitol is a national landmark and a common symbol for democracy. It is also notable for its impressive grounds and gardens, which cover more than 40 acres (16 hectares). These include a tree-lined avenue called the Long Mall that runs for more than a mile between the Capitol and the President's House. The National Garden, located next to the President's House, contains memorials and monuments including the World War II Memorial and the Korean War Veterans' Memorial. The Capitol's dome can be seen from many miles around, making it a popular spot for photographers. In addition, the grounds contain more than 9,000 plants, including 400 species of trees. The Congressional Gardens are open daily except when in use for a legislative session.