The church of San Francisco Church in Quito was built in the 16th century. For centuries is was the "richest" church in South America, its altar room is gold-plated (Inka-Gold, that was) from floor to ceiling.
Its surroundings, the old town, were the first to be anounced UNESCO World Heritage Cultural Site (with Krakow, Poland) in 1978.
Built in Italian style in 1873, the Casa Rosada, "Pink House", is officially known as the Palacio de Gobierno, the Government Palace. It is the official seat of the Executive Branch of the government of Argentina.