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Is the breast-shaped shadow on St. Mary’s Cathedral an accident or a clever prank?

Chan Rodgers
St. Mary's Cathedral from the intersecton of Haight and Octavia, Nov. 13, 2015.

KALW listener, Chan Rodgers was curious about one of San Francisco’s most distinctive buildings, and the provocative shadow it sometimes casts. So, he posed this question to our Hey Area project:

“I've often wondered if the breast-shaped shadow on St. Mary's Cathedral was a very clever architectural prank or just an accident.”

KALW Audio Academy fellow Amber Miles collaborated with Chan to bring us this story.


Modern design  

St. Mary’s Cathedral has a unique concrete design. Its simple square base twists skywards to form the shape of a cross — making the cathedral stand out as one of the city’s most recognizable landmarks.

KALW listener Chan Rodgers says he’s “always been impressed with its modern design. I mean, this is an amazing and very complex form.”

Chan is a semi-retired academic, an avid architecture enthusiast, and bit of history buff.

Chan says that San Francisco Chronicle columnist Herb Caen “made a lot of good, lighthearted fun of the building, where he called it Our Lady of Maytag because he thought the building looked like a washing machine agitator.”

There are many monikers associated with St. Mary’s, but one of the most titillating references the regular afternoon appearance of a breast-shaped shadow on its sweeping concrete roof. They call this phenomenon the “Two O’Clock T***y.”

Our first thought was to track down the architects responsible for the cathedral’s design. Sadly, they had all passed on to the great drafting table on the sky.

So, we expand our search. I make a trip down to the Department of Building Inspection, and the Records Department actually has reams of good stuff from St. Mary’s — old blueprints and building documents — all on microfilm.

As I scan through the film, something in the right-hand margin of the blueprint catches my eye: names, etched there all tight and white in miniscule lettering.

I crank the lens and zoom in. Among the names of the senior architects I already knew of, I see a new one: a project architect named William Schuppel.

I found a handful of phone numbers for William Schuppel online. They were all dead ends expect for one, which lead me to a voicemail box.

At the beep I left a message and crossed my fingers.

The last living architect

William Schuppel himself eventually called back. Chan and I met him at his modern Mission Bay apartment complex.

There, he informed us that it was Pietro Belluschi, an Italian-born architect who was ultimately responsible for the cathedral’s design.

The design that uses something called a hyperbolic paraboloid. It’s a complicated geometric form.

“Sometimes it's been compared to the shape of a pringles potato chip,” Chan says. “Architects love this because you can build these very gracefully shaped smooth surfaces using only straight building components.”

Basically, to build the roof, Belluschi took two of these Pringles and broke them into quarters. He then used two quarters to construct each concrete arm of the cross — and in doing so, created a structure that would, intentionally or not, cast the now famous breast-shaped shadow.

Chan asks about the public’s response to the cathedral when it was first built.

“[I]t made quite an impact,” William says. “And I think it was quite a popular building, but I think there was also some merriment directed towards it by people like Herb Caen.”

Broaching the breast

So William was familiar with some of good natured jokes around St. Mary’s. But did he know about the shadow? The time had come to broach the breast!

But before either of us could say anything, William beat us to it.

After talking about Herb Caen, William goes on to say how “the shadow, at certain times, looks like the breast of a woman.”

And that is all Chan needed to dive in to his theory on the shadow.

“I think it's brilliant,” he says. “What could be more appropriate for a church dedicated to the Blessed Virgin than the shape of a human breast? ... the mischievous 14-year-old in me likes to think that this was intentional, and that there was an architect so brilliant that he thought of this.”

William laughs and tell us that he didn’t know about the shadow ‘til the newspaper wrote about it.

So, the shadow may not have been a purposeful prank, but at least its last living architect finds it as entertaining as the rest of us.  

Ceremonial shadow viewing

Chan invited some fellow architecture-lovers to gather on the corner of Rose and Octavia streets in San Francisco.

It is a bright day, and the shadow was clearly visible. I wouldn’t call it breast-like exactly, not yet anyway. It is more pointy than perky, topped with a hard edge that jutted out diagonally across the cathedral’s roof.

One of the viewing party members suggests that perhaps “when it dissociates from the other shadow the nipple will perk up.”

We stand on that corner for over an hour, sunlight in our eyes, squinting up at St. Mary’s and coaxing the shadow to fill out and achieve its full-bosomed potential.

But it never happens.

Maybe you’ll find yourself at the corner of Rose and Octavia at the right time of year, at the right time of day, and be lucky enough to see the shadow in all its curvaceous glory.



Credit Amber Miles
KALW listener and Hey Area questioner Chan Rodgers.

Chan Rodgers is a physician working in biomedical informatics and teaching part-time at a

prominent Bay Area medical school, living in West Berkeley. He’s been fascinated with architecture since he was a little kid. It was that interest combined with a healthy dose of mischief and an appreciation for Bay Area quirks that lead Chan to write to Hey Area, to find out more about a building shadow that has caused some controversy.


This question came to KALW through Hey Area, a crowdsourced, collaborative reporting project. Got a question for Hey Area? Ask it below.



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