The National Congress towers over Avenida de Mayo, its occupants theoretically keeping a watchful eye on the president's Casa Rosada down the street. The capitol building, built in 1906, combines elements of classical Greek and Roman architecture and is topped with an immense central dome modeled after its counterpart in Washington, D.C. Today, the building cannot accommodate the entire congressional staff, some of whom have spilled over into neighboring structures.

Plaza Congreso was designed in 1910 to frame the congress building and memorialize the centennial of a revolutionary junta that helped overthrow Spanish rule in Argentina. Stroll around the square and its surroundings to see a number of architectural landmarks, theaters, sidewalk cafes, and bars.