The unusual doorway at the church of Mission Espada has long been a curiosity to visitors and historical researchers struggling to explain its distinctive form.
For years, scholars have said the doorway’s irregular form was the likely result of a mistake.
Had the stone been arranged differently, the doorway would have been two feet wider, with outer lines of the arch above it
forming a continuous semicircle, rather that jutting inward. But newer research suggests the native mason's used clever creativity in the face of a limited budget and a scaled-down church design.

Mission San Francisco de la Espada is a Roman Rite Catholic mission established in 1690 by Spain in present-day San Antonio, Texas, in what was then known as northern New Spain.
a UNESCO World Heritage Site