Mission Nuestra Señora de la Purisima Concepción de Acuña: This handsome stone church was dedicated in 1755, and appears very much as it did over two centuries ago. It stands proudly as the oldest unrestored stone church in America. In its heyday, colorful geometric designs covered its surface, but the patterns have long since faded or been worn away. However, original frescos are still visible in several of the rooms.