Founded in the twelfth century in the region of Lake Titicaca, the Andean empire of the Quechua-speaking Incas grew until, by the fifteenth century, it extended from southern Colombia in the north to Argentina and central Chile in the south. Their society was rigidly divided into classes: the nobility, their servants, and the common people. The Incas worshipped the sun and the moon, and believed that Manco Capac, their first emperor or inca, was descended from the sun. An extensive network of roads was built to facilitate control over the empire from its capital in Cuzco. The Incas left an impressive heritage of monuments, including the palace complex of Machu Picchu. The empire collapsed in 1533 when the Spanish conquistador Francisco Pizarro had the emperor Atahualpa executed and occupied Cuzco.