La Casa Rosada is the executive mansion and the office of the President of Argentina. It was built in 1580 and is located at the eastern end of the Plaza de Mayo in the capital city Buenos Aires. La Casa Rosada distinguishes oneself in being colored baby pink in 1873, reportedly in order to defuse political tensions by mixing the red and white colors of the country's opposing political parties: red was the color of the Federalists, while white was the color of the Unitarians. An alternative explanation suggests that the original paint contained cow's blood and chalk because of having water-repellent and fixing features. As the “Pink House” was built on the erstwhile town fortification, its exterior was often changed. Some of the concerned architects were: Edward Taylor, Carl Kihlberg, Enrique Aberg and Francesco Tamburini. Since 1957 la Casa Rosada houses a museum of objects relating to former presidents and belongs today to one of the National Historic Monuments of Argentina.