BonnieArbittier_missions_national_park_historiacl_rangers_espada_aqueduct_8-25-2017-5 San Antonio Missions National Historical Park Mason Stephen Siggins hammers into the side of the Espada Aqueduct. Credit: Bonnie Arbittier / San Antonio Report San Antonio Missions National Historical Park Mason Stephen Siggins hammers into the side of the Espada Aqueduct.