The architectural styles of these churches vary from Gothic to Renaissance to Churrigueresque and Neoclassical, with many mixing elements of two or more. A number also have Talavera tile as a decorative feature, which is common in Puebla. A few have intricate stucco work done by indigenous hands. These churches together contain more than 300 works of art from the 16th to 19th centuries, which have a total value of millions of dollars. Increases in the theft of religious art have led to a number of measures being taken to protect them. Over a decade ago, churches were routinely open during the week, but now many are not. When they are open, many have at least one guard on duty, or in the case of the Nuestra Señora de los Remedios church, video surveillance. Some churches put replicas of the works on display, such as in the friary of San Gabriel. Some do not permit photographs or video of the church interiors.