 Declared a national monument in 1933, the monastery of San Agustín was built between 1539 and 1580 with most of the work being done after 1550.The walls are of rubble-stone construction and covered in plaster, topped by battlements, and the overall appearance is that of fortress.The crown of battlements, the single bell tower, the open chapel and the Plateresque facade identify the complex as a classic 16th century religious construction.