Montevideo's most important plaza is Plaza Independencia, located between Ciudad Vieja and downtown Montevideo. It starts with the Gateway of The Citadel at one end and ends at the beginning of 18 de Julio Avenue. It is the remaining part of the wall that surrounded the oldest part of the city. Several notable buildings are located here. Solís Theatre The Solís Theatre is Uruguay's oldest theater. It was built in 1856 and is owned by the government of Montevideo. In 1998, the government of Montevideo started a major reconstruction of the theater, which included two US$110,000 columns designed by Philippe Starck. The reconstruction was completed in 2004, and the theater reopened in August of that year. The plaza is also the site of the offices of the President of Uruguay (both the Estévez Palace and the Executive Tower). The Artigas Mausoleum is located at the center of the plaza. Statues include that of José Gervasio Artigas, hero of Uruguay's independence movement; an honor guard keeps vigil at the Mausoleum.