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Kari Jones standing next to Presidio Archaeology Field Station sign

Jul 8, 2016

Discovery of the Month: Uncovering the Foundations of El Presidio

Presidio archaeologists uncover stones from the first Spanish “El Presidio” fort from 1815.


Each May, Presidio archaeologists are back at work excavating around Pershing Square at the Main Post, so we bring you this Discovery of the Month from the FIELD! This month, our report comes from Archaeologist Kari Jones.

“At first glance, the rocks you see below may not seem like much, but these stones are actually the foundations of the Spanish ‘El Presidio‘ fort from 1815,” Kari shares. “We discovered these foundations in our 2014 and 2015 excavations. They’re in great shape despite having been built 200 years ago, and we’re uncovering more of the buildings as excavations continue.”

According to Kari, “To build the adobe buildings of El Presidio, the Spanish would dig a trench and carefully place serpentinite stones to form the foundations.” They would then fill in the trench and stack adobe (AKA, sun-dried mud) bricks on top to form the walls of the building. “What’s exciting about this photo is that you can actually see the ground where the builders stood to dig the trench, lay the foundations, and build the walls of the western wing of El Presidio in 1815,” Kari said. “These buildings stood and were used by the Spanish and eventually the United States Army until 1906 when they were so badly damaged in the San Francisco earthquake that the Army tore them down. This buried the foundations, therefore preserving them until we uncovered them over 100 years later.”

The archeology team is currently excavating in Pershing Square to uncover the layers of history buried just beneath our feet. “Our goal is to determine where the buildings were and how they were used,” Kari explained. “Were they administrative buildings, or barracks for enlisted men or officers? Parts of Pershing Square may have even been used as a corral for the animals of El Presidio! We hope our careful study of these buildings and the artifacts associated with them will allow us to tell the hidden stories of the families who once called this place home.”

Here you can see the foundations of El Presidio de San Francisco and the 1815 ground surface while Claire Yancey, one of our archaeologists, works to uncover more.

Learn more about our Archaeology program >>