The San Antonio River united and sustained the five missions, providing the water without which residents, crops, and livestock would not have survived. The oldest mission, San Antonio de Valero, the Alamo, stood north of here in what is now downtown San Antonio, while Mission Concepción was established farther south along the river in 1731. Its church, completed and dedicated in 1755, is the least restored building in San Antonio Missions National Historical Park and the oldest unrestored stone church in America. Mission Concepción is recognized in the World Heritage inscription for the significance of its Spanish Colonial architectural features, especially its twin towers, carved limestone entrance portal, original vaulted roof and dome, convento and corredor, and colorful interior frescoes painted more than 250 years ago. Like Missions San José, San Juan, and Espada, Concepción still serves for church services, and water from the river was channeled to mission fields for livestock and crop irrigation. Although the Mission Concepción Acequia was closed in 1869, parts of its channel continued to be used for irrigation in the late 1800s.