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.

The Church's disposition provides for a solar phenomenon on or around Oct. 4 — the feast day of St. Francis of Assisi,
when the light from the rising sun shines through a window above the doorway, illuminating the rear wall behind the altar.