Among the most striking features of the monasteries of the Mixteca Baja are their capillas abiertas. These graceful open-air chapels, found only in the New World, look like unfinished, roofless churches, or cathedrals chopped in half. They face out onto huge open areas where the idea was that mass conversions of and services for indigenous people, too numerous for the church to accommodate, would take place. They are designed for congregations of thousands; the very same people whose prodigious labour produced these vast churches in the first place. Sadly, even by the time they were first completed, those populations had been decimated by disease and the demands of the Spanish overlords; the capillas became vast white elephants, testament to a vanished population.