A capilla abierta or “open chapel” is considered to be one of the most distinct Mexican construction forms. Mostly built in the 16th century during the early colonial period, the construction was basically an apse or open presbytery, containing an altar, which opened onto a large atrium or plaza. While some state that these were constructed by friars because the native peoples of that epoch were afraid to enter the dark confines of European-style churches, the more likely reasons for their construction were that they allowed the holding of Mass for enormous numbers of people and the arrangement held similarities to the “teocallis” or sacred precincts of pre-Hispanic temples. While open chapels can be found in other places in Spain and Peru, their systematic use in monasteries and other religious complexes, leading to a regularization of architectural elements, is only found in Mexico.
The capilla abierta was an open apse or presbytery of a reduced size, located on the ground floor or the first floor (which allowed for greater visibility)and opening onto a large atrium or plaza. The main idea is to allow the large number of people to congregate in front of a single altar. In Mexico, three types of open chapels came to be used: the “salon” or “mosque” type found in Cholula and Puebla, distinguished by its front arcade with Moorish arches, the “portico” type, which was a porch area in front of the cloister and the balcony type, located on the upper floor or roof. Portico style chapels can be seen in Tlalmanalco, Atlatlahucan and Cempoala, with the best known of the balcony type being found in Acolman, Mexico State.
Almost all open chapels were part of a larger structure, whether it was the main church or the cloister of the monastery. One significant exception is the chapel in Actopan, Hidalgo.