One Of New York City's Tallest Buildings Had A Design Flaw That Nearly Toppled It

One of New York City's tallest builidngs nearly toppled over due to a design flaw.

Roman Mars' podcast called 99% Invisible, which covered design stories big and small, revisited the story of 601 Lexington, which was called the Citicorp when it was built in 1977.

The 59-story tower in Midtown Manhattan was the seventh-tallest in the world when it was completed, according to Slate.

The silver, angled top pointing toward the sky make it easy to pick out of the skyline, even today, but what remains exceptionally unique to the structure is the first nine stories — stilts the others rest on.

The design originated to accommodate St. Peter's Lutheran Church, which occupies one of the corners at 53rd Street and Lexington Avenue. The church agreed to the building on the condition that the skyscraper be built around the church and in the airspace above it.

William LeMessurier, the lead structural engineer had the idea for the design while at a Greek restaurant and scribbled it on a napkin, according to Slate.

There are three things going on with the building according to Slate at 99% Invisible that set it up for a potential disaster.

1. Nine-story stilts suspend the building over St. Peter's church. But rather than putting the stilts in the corners, they had to be located at the midpoint of each side to avoid the church.

2. Having stilts in the middle of each side made the building less stable, so LeMessurier designed a chevron bracing structure-rows of eight-story V's that served as the building's skeleton.

3. The chevron bracing structure made the building exceptionally light for a skyscraper, so it would sway in the wind. LeMessurier added a tuned mass damper, a 400-ton device that keeps the building stable.

Only all of the above didn't come together. If a gust strong enough came through New York City, the building would fall. No collapse, fall over. You get a sense of the difference between the two catastrophes in the YouTube video below.

The scariest part about the flaw was that it took until 1978, when an undergraduate architecture student studying the tower, for the danger to be realized and addressed.

After receiving a phone call from the student, LeMessurier calculated that a 55-year wind could topple the tower and upon further study, more problems became apparent.

"LeMessurier realized that a major storm could cause a blackout and render the tuned mass damper inoperable. Without the tuned mass damper, LeMessurier calculated that a storm powerful enough to take out the building his New York every 16 years," according to Slate and 99% Invisible.

Repairs were made in secret, ever as Hurricane Ella approached but it never made landfall and it wasn't until 1995 the story was made public.

Joe Morgenstern overheard it being told at a party, and interviewed LeMessurier for The New Yorker.

There is another bizarre twist to the story you read about in the article, or watch in this YouTube video.