Believed to be the first gothic structure west of the Mississippi, the chapel had a design flaw: a conventional stairway to the choir loft could not be installed without adversely impacting the diminutive chapel's seating capacity as well as its aesthetics.
Seeking divine guidance, the Sisters made a Novena (a prayer said each day for nine days) to their patron saint, Saint Joseph the Carpenter.
As legend has it, upon the ninth and final day of the Novena a mysterious carpenter arrived to design and construct a circular stairway to the choir loft. The tools upon his donkey were just a saw, a T-square, a hammer, and tubs in which to soak the wood.
His "miraculous stairway" contains thirty-three steps in two full 360 degree turns. The stairway has no center support nor is it held from its sides -- its full weight rests on its final tread.
Upon completion of the stairway the carpenter disappeared without seeking payment. No records have ever been found for the purchase of the materials with which the stairway was built.
Many sisters believed the craftsman to have been an embodiment of Saint Joseph the Carpenter.
Originally built without a railing, its use was a daily reinforcement of faith by both sisters and students. In the 1880's the banister was added.
Engineers and architects marvel at the stairway; there is no known duplication of its design.