San Miguel Chapel, the Spanish colonial mission church you are facing, was originally built around 1610 and is often called the oldest church building in the continental United States. This was probably the first church in the new settlement, built across the Santa Fe River from the villa proper in the neighborhood known as the Barrio de Analco, an area once inhabited mainly by native people including Tlaxcalans who had accompanied the Spanish settlers from Mexico. The chapel you see has been rebuilt twice — once in the mid to late 17th century and again in 1710 following the Pueblo Revolt — and earlier pieces of the building may have been reused, though to what extent is unclear.
Inside, note the wooden reredos, which was added in 1798 and includes a wooden statue of Saint Michael that dates to at least 1709. San Miguel is a contributing property in the Barrio De Analco Historic District, a U.S. National Historic Landmark, and as of 2020 Mass is still offered here on the first Sunday of the month at 3pm. Beyond the chapel walls, the Santa Fe River divides this Barrio de Analco from the villa proper.