The "Argentine National Congress" is the legislative branch of the government of Argentina. Its composition is bicameral, constituted by a 72-seat Senate and a 257-seat Chamber of Deputies. The Congress building is located in Buenos Aires, at the western end of Avenida de Mayo (at the other end of which is located the Casa Rosada). The Kilometre Zero for all Argentine National Highways is marked on a milestone at the Congressional Plaza, next to the building.