On May 1, 1718, Governor Martín de Alarcón founded the Spanish colonial settlement of San Antonio de Béxar with roughly 72 settlers, soldiers, and clergy, and this is its historic core. The founding was deliberately ambitious: New Spain's government wanted to establish a permanent settlement on the road from Mexico City to the missions of East Texas, creating a reliable waypoint in the vast and largely unmapped territory of Tejas. The settlement had three interlocking components: the Mission San Antonio de Valero (which would become the Alamo), the Presidio San Antonio de Béxar (the military fort), and the civil settlement of Villa de Béxar.
Within a generation, the settlement had grown enough to require additional missions, and the chain of five missions that now constitutes the UNESCO World Heritage Site was established between 1718 and 1731. For nearly a century, San Antonio de Béxar was the capital of the province of Tejas — the seat of whatever governmental authority Spain exercised over this enormous northern frontier. When Mexico won independence from Spain in 1821, the settlement became the capital of the province of Texas under the new republic.
The city that surrounds you grew outward from this exact spot. Every street in old downtown San Antonio traces its origin to the 1718 plan.