The varied and influential inhabitants of San Agustín de Callo have contributed to the unique blend of architecture which creates the individual character of the house. In the main courtyard it is possible to see three distinct styles, Inca (Imperial style 15th century, construction style which the Incas used for their temples and palaces), Spanish Colonial (18th century) and Republican (19th century). The Hacienda has been written about by the famous chronicler Cieza de Leon (1536). This Inca Palace or temple was built by Tupac-Yupanqui (Inca Emperor) or Huayna-Capac in the 15th century. San Agustín de Callo constitutes the only lived-in museum of Inca Imperial and Spanish Colonial style.

By far the most impressive sights are the perfectly carved volcanic stone walls of two of the Inca rooms which have survived the centuries and now serve as chapel and dining room.

Surrounded by the smoke-blackened walls of the dining room, one can marvel at the infinite precision of the stonemasonry, a monument to the unrivalled craftsmanship of the Incas, and admire the stunning view of Cotopaxi, the highest active volcano in the world. This magical spectacle was extolled by Alexander von Humboldt who visited the Inca site in 1802 included his observations in his work "Vue de Cordilleres et Monuments des Peuples Indigenes de L'Amerique" Paris 1810.