I recently went to San Antonio for a business convention and had a little time to run around the city and see the sites.
This is the interior of Mission Concepcion which dates from the 1730's which is pretty freaking old for Texas.
The Alamo
This is Mission Espada which also dates from the 1730s.
Rosas Window, which is considered to be one of the greatest examples of Spanish colonial architecture in the southwest at Mission San Jose, which dates from the 1720s.
All of these and more missions are located within 20 miles of downtown San Antonio.