How was a mission site chosen? What factors went into the location of a mission? Who decided where to build a mission? When was Mission San Miguel Founded? Mission San Miguel Arcángel was founded on July 25, 1797 by Fr. Fermín de Lasuén and Fr. Buenaventura Sitjar.  Important Steps Before establishing a Spanish mission in Alta California, a number of steps had to be taken in order to ensure that it would be successful. Both the Spanish government and the Franciscan Order had to agree that a mission was desirable. A mission site had to be found, and the local native people had to approve. The story of the founding…