An introductory study of the architectural history of Spanish Colonial Guam, this work examines Spanish civil and military construction in the villages of Agana (Hagatna) and Umatac (IHumata) in the 18th and 19th Centuries. The history of these buildings has received scant attention other than as a footnote to other structures erected under the administration of one governor or another. As with most histories, the accolades have gone to the civil or ecclesiastical hierarchies who paid for the buildings, and not to those who actually designed and constructed them. This study addresses this oversight in hopes that more will be gained from archival sources, stimulating others to write on Guam’s architectural history.