Alfonso Caso started his archaeological career as a professor, and also former student, at the University of Mexico from 1918 to 1940 where his specialty was Oaxacan history and culture. From there he became the Head of the Archaeology department at the National Museum in Mexico from 1930 to 1933 and soon became the director of the department from 1933 to 1934. During his time as an archaeologist, Caso directed an excavation of the Zapotec city of Monte Alban in Oaxaca in 1931 and was the first person since the city’s abandonment to rediscover the secretes of the nearly forgotten city. Alfonso Caso ended up spending 16 seasons discovering the hidden gems of the overgrown city.
Over roughly the next 12 years, Caso made discoveries at Monte Alban that opened up an untold story of Oaxacan cultures. One of his most remarkable discoveries was that of Tomb #7 which showed evidence of the Mixtec people occupying the city after the displacement of the Zapotec people sometime before the Spanish Conquest. Although Tomb #7 is the most famous tomb at Monte Alban it is not the only major discovery found among the other tombs. Also found within some of the 170 on site tombs, Caso found a series of vivid polychrome frescoes, sacred motives, painted figurines, and also the remains of Kings and Priest which points to the ancient site being used as a necropolis. Caso also uncovered evidence pointing to Monte Alban having five major stages of history which correlates to separate ancient sites and dates back to 800 BCE. The correlated text found at various sites helped Caso to be the first person to decipher the Mixtec Codices and provide an accurate chronological history of Monte Alban which brought them closer to understanding the Zapotec and recently discovered Mixtec way of live at Monte Alban.