The church faces the plaza in the Spanish urban tradition. The third church on this site, it was built by Oblate priest-architect Kéralum, who also designed the church in Brownsville (
BS9). The outline of the second church of 1789 is laid out in the pavement in front of San Agustín. Its small size reflects the diminutive scale of early Laredo when compared with the more sizeable late-eighteenth-century religious buildings of nearby Guerrero and Mier on the Mexican side of the Rio Grande. The narrow Gothic Revival nave of San Agustín, constructed in plastered sandstone, was completed in 1872. Its 1877 bell tower became Laredo's version of London's Big Ben when it was heightened in 1922 with a four-faced clock level that was visible from Nuevo Laredo. Next door at 201 San Agustín Avenue, the former San Agustín Parochial School (1927) by Leo M. J. Dielmann is a three-story Gothic Revival structure built to meet the demand for educational services created by the influx of immigration caused by the Mexican Revolution, which doubled the population of Laredo in less than a decade.