The San Agustin Historic District functioned as the original civic, religious, and commercial core of Laredo from its founding in 1755 by Tomas Sanchez de la Barrera y Garza. Laid out around a central plaza, the district's everyday use centered on the plaza itself, which served as the town's public gathering space and marketplace, and on the adjoining church site, formally reserved when the townsite was surveyed in 1767, where residents worshipped first in a simple palisade structure before a permanent stone church was completed by 1780. As Laredo grew under Spanish and later Mexican and Texan rule, the plaza and surrounding blocks functioned as the seat of local governance and commerce, with civic buildings, homes, and businesses clustered around the church that would become San Agustin Cathedral. The district's role as the town's administrative and religious anchor persisted for generations, though by the twentieth century commercial growth shifted Laredo's center elsewhere, prompting preservation efforts and the 1973 creation of a protected historic district. Today San Agustin continues to function much as it did originally: the cathedral remains an active parish church, elevated to cathedral status in 2000 with the creation of the Diocese of Laredo, while the surrounding district serves as a preserved historic downtown containing museums, city offices, and the restored plaza, making it a living rather than purely commemorative site.