the Equitable Building, in the heart

of New York City's Financial District,

might not seem to stand out.

But according to legend, this skyscraper

was once considered so obscenely large that it led

to the first major zoning law in the United States.

And because of that law, it was

the last skyscraper of its kind.

(light contemporary orchestral music)

When it was completed in 1915, the Equitable Building

was the largest office building in the world,

and an engineering marvel.

The building had one problem: it was too big.

Designed to maximize rentable office space,

it was basically a 40-story H-shaped box

crammed onto an acre-sized city block.

When it was built, New Yorkers were in an uproar

over the "evil effect" of its size.

Neighbors complained of the enormous shadow

that cast nearby buildings and streets

into complete darkness.

Meanwhile, developers worried that a glut

of these huge office buildings

would hurt real estate values.

At the time, New York had no laws

restricting the size or height of office buildings.

But as new technology was pushing skyscrapers

like the Equitable Building to unprecedented scale,

the outcry for regulation reached a breaking point.

Then, something happened.

Within a year a law was passed that

effectively made skyscrapers like the Equitable Building

impossible to build again.

It was called the 1916 Zoning Resolution,

and it was the first comprehensive zoning law

in the United States.

To be clear, the Equitable Building

didn't directly cause the 1916 Zoning Resolution.

It was simply the ultimate scapegoat

in a debate that had been heating up for years

as new technology made skyscrapers bigger and bigger.

Instead of enacting a fixed height limit,

like other cities had done,

the drafters of the resolution developed an ingenious plan

based on something called a setback principle.

Here's how it worked.

Depending on the district, a building's height

could not exceed a certain ratio to the width of the street.

In a 1 1/2 district, for example,

the maximum height was limited

to 1 1/2 times the street width.

A building could gain extra height, however,

if it were set back from the street.

In a 1 1/2 district a building could rise another three feet

for each foot that it was set back from the street.

Furthermore, in any district, 25% of the lot

had no height limit at all.

Working within these constraints,

architects began to creatively conform designs

in what became a characteristic style,

starting full width at street level

and tapering off in steps as it rose in height.

And once you're aware of it you start

to see it throughout Manhattan.

(upbeat contemporary chamber music)

And the intended effect of

making New York's dense streets seem more open,

for the most part actually works.

The Zoning Resolution went beyond height limits too.

It also set rules for how land could be used

in specific areas of the city,

such as prohibiting industrial work

in residential or business districts.

Around the same time, other American cities

began to adopt similar zoning plans.

Six years later, Congress passed a law

based partly on New York City's example

as a blueprint for zoning nationwide.

By the 1960s, New York had grown significantly,

and so the city passed a new resolution

modifying the setback principle

to accommodate for new building designs.

Meanwhile, the Equitable Building,

now a historic landmark and undergoing a major renovation,

is a monument to a bygone era,

one whose excesses led to New York's iconic skyline,

which you'll never look at the same way again.