On the warm, humid morning of August 20, 1775, the Tucson Presidio was established by Regular Spanish Army Lt. Colonel Hugo O’Conor. O’Conor, of Irish descent, was Inspector General and had made a name for himself on the frontier of New Spain.  The construction of the fort probably started the following October.  The Tubac garrison and families moved north in late October of 1776 occupying the earthen berms and palisade that was the Tucson fort. The first correspondence was written from Tucson by Col. Juan Bautista de Anza in November of 1776.

The image above is one of very few existing historic sketches showing the original Presidio San Agustín del Tucson.  We can see people visiting outside and more people gathered in the small chapel. 

The fort was small and poorly constructed. In 1782, after a large Apache assault, an 8 to 12 ft high adobe wall was constructed that was about 700 ft long on each side.  The post was continually improved until it reached its maximum size of approximately 11 acres. The land enclosed in these walls sat in what is now present day downtown Tucson, approximately inside the streets of Church, Washington, and Congress, and up to the banks of the Santa Cruz River (which was flowing at that time.)

This map, based on the 1883 Sanborn Fire Insurance Map, was drafted in the 1940s.

This map, based on the 1883 Sanborn Fire Insurance Map, was drafted in the 1940s. The red outlines where the original Presidio walls were, by this time they were mostly buried by newer construction.

A sketch from Tom Sheridan’s Los Tucsonenses shows the enclosed space of approximately 11 acres. The pathway along the front wall corresponds to current day Main Avenue. At that time it was referred to as El Camino Real (the Royal Road). Tucson was among the largest of the frontier presidios.  Tucson’s torreones (towers) were state of the art, allowing defense along the walls. The square style torreones are found on most post-1772 presidios.

In 1821, Spain accepted Mexico’s Independence after an eleven year conflict. For residents of the Tucson Presidio life did not change much. The Mexican Army did not arrive for a few years and when it did the Spanish flag was taken down and the Mexican flag was put up.

The Presidio remained in use as a protective fort until the Americans entered Tucson in March 1856. By then, residents were interested in newer constructions and bricks from the Presidio were taken and used.
Today’s Presidio Museum gift shop and exhibit rooms are housed in the Siqueiros-Jacome House, constructed in the 1860s and 1870s. Soil to make the adobe bricks was mined from a large pit in the backyard.

The last standing segment of the wall was torn down in 1918. The location of the original Presidio wall is marked today in Tucson’s sidewalks, and demonstrate how extensive the fort was.

Pavement marker in a Tucson sidewalk showing the original Presidio wall foundation.

Today’s reconstruction is located on the site of the northeast corner of the fortress. Markings on the ground show the location of walls, with the new walls offset to preserve the original adobe foundations.