Established 1731, favorite of many students of Spanish period in Texas, and popular with photographers. The little church building, restored several times, is still in use. Ruins of walls that once surrounded the mission compound; foundations of a granary; baluarte, or fortified tower, can still be seen. Espada Rd. south. Near the mission is an aqueduct over Piedras Creek, part of mission's irrigation system built in 1740s. System includes dam on San Antonio River and acequia (irrigation ditch) still in use after more than 200 years. The aqueduct is a National Historic Landmark.