Mysterious and Amazing History

Santa Fe, New Mexico is home to the famous spiral staircase built of wood. In 1878, the architect of Chapel of Our Lady of Light died, leaving them with a choir loft, but no access to it. The chapel was visited by architect, craftsmen, and carpenters, but none could come up with a way to build a staircase with remodeling the interior of the chapel and taking up valuable space. So the nuns began to pray for an answer.

Here begins the mystery...after eight days of prayer, an elderly man with a mule showed up at the door with a box of simple tools. He took one look, and said he'd build them their staircase. Alone, the man started working on the staircase using no nails or screws. After some time, the staircase was complete. A work of art without central support. The carpenter quietly left without payment. The nuns planned a great feast, but no one knew what happened to the elderly man.

No one knew where he stayed, and the local lumberyard had no record of the purchase of wood. With the mysterious disappearance of the humble carpenter, the nuns began to wonder it was St. Joseph himself, the earthly father of Jesus, who was sent to build their staircase. When they counted the stairs, they found there were 33, the number of years Jesus was on Earth before ascending to heaven.

There have been some who claim to know who may have built the spiral staircase of Loretto Chapel. Some say it was Johann Hadwiger, a master carpenter. After his death, his grandson found a sketch of a spiral staircase with 33 steps in his old toolbox. Perhaps it was Francois-Jean Rochas, whose obituary in the Santa Fe New Mexican newspaper read "an expert worker in wood who built the staircase in the Loretto chapel".

So who built the mysterious spiral staircase?

via Mysterious and Amazing History.

Looks cool, but this is one of those stories that people repeat without bothering to look up the truth about it. Here is the snopes analysis:

... Although winding staircases are somewhat tricky to build because the form is not well-suited to
bearing weight and generally requires additional support, the one at Loretto is not quite the miracle of
architecture that subsequent legend has made it out to be.

For starters, the Loretto staircase was apparently not all that fine a piece of work from a safety standpoint.
It was originally built without a railing, presenting a steep descent that reportedly so frightened some of
the nuns that they came down the stairway on their hands and knees.  Not until several years later did another
artisan (Phillip August Hesch) finally add a railing to the staircase. Moreover, the helix shape acted like
what it resembles, a big spring, with many visitors reporting that the stairs moved up and down as they trod
 them.  The structure has been closed to public access for several decades now, with various reasons (including
 a lack of suitable fire exits and "preservation") given for the closure at different times, leading investigator
 Joe Nickell to note that "There is reason to suspect that the staircase may be more unstable and, potentially,
unsafe than some realize."

Although the Loretto legend maintains that "engineers and scientists say that they cannot understand how this
staircase can balance without any central support" and that by all rights it should have long since collapsed
into a pile of rubble, none of that is the case.   Wood technologist Forrest N. Easley noted (as reported by
the <I>Skeptical Inquirer</I>) that "the staircase does have a central support," an inner wood stringer of
such small radius that it "functions as an almost solid pole."  As well, Nickell observed when he visited
Loretto in 1993 that the structure includes an additional support, "an iron brace or
<A HREF="http://www.csicop.org/si/9811/stair2.jpg" TARGET=brack>bracket</A> that stabilizes the staircase
by rigidly connecting the outer stringer to one of the columns that support the loft."  Nickell concluded:

... "It would thus appear that the Loretto staircase is subject to the laws of physics like any other."
All in all, nothing about Loretto's design or manufacture evidences any sign of the miraculous.  The staircase
(and the chapel that houses it) is, however, now part of a privately-owned museum operated for profit,
a situation that provides its owners with a strong financial motive for promulgating the legend. ... 

via Snopes