Constructed during the onset of  the Great Depression, the Empire  

State Building became a  symbol of American innovation  

and a marker of what the United States could  achieve, even during its darkest times.

Standing as the world's tallest  building for 40 years of its life,  

the grandeur and scale of the Empire  State inspired near-universal awe  

and cemented it as the defining  structure of New York City.

Now, as the structure  approaches its 90th birthday,  

a ten-year modernisation programme  has revamped the groundbreaking  

Otis elevator system that enabled the  original construction of the building,  

improved energy efficiency and brought this  iconic 1930s skyscraper into the 21st century.

The early 20th century was a time of  great innovation and change across the  

United States - and advancements in building  materials combined with a booming economy and  

growing population gave rise to the skyscraper.

First appearing in Chicago and then across the US,  

perhaps no American city saw a  greater transformation than New York.

Taking the title of “world's tallest  building” from itself no less than five  

times between 1909 and 1931, New York City's  race for the skies captivated onlookers  

as taller and taller skyscrapers  began to dominate the skyline.

But the crash of 1929 brought this boom to an  

end and the demand for tall  buildings evaporated overnight.

With two years of planning behind them,  developers at the Empire State decided  

to proceed with their project, fearing the even  greater losses that would come with cancellation.

Starting in 1930 and completing in just 14 months,  

the skyscraper set new records; becoming  the tallest structure ever built,  

the first building to surpass 100 storeys and  housing the world's fastest elevators of the day;  

an innovative installation by Otis that  made the building's immense height viable.

Though it's since been eclipsed  by dozens of taller structures,  

the Empire State's form and observation  decks, along with countless appearances  

across popular culture, have retained its status  as one of the world's most famous buildings.

Today, 90 years after its arrival on the skyline,  

the Empire State Building is a global leader  in sustainability and energy efficiency.

After a decade-long project to upgrade,  the building has improved efficiency,  

retrofitted interiors and overhauled  the Observatory Experience.

Each of the building's 6,514 windows have  been retrofitted with high-performance glass  

and a new lighting system that  adapts to the levels of natural  

light entering the floor-plate has been installed.

The heating system has been fitted with reflective  barriers to reduce heat loss and lower the  

building's carbon footprint while a multi-year  elevator upgrade - undertaken by the original  

system installers Otis - will move passengers 50%  faster during peak times than the original system,  

while returning energy to the building's  grid through its regenerative drives.

But while many of these upgrades will be  systematic and make the Empire State one  

of the most historic skyscrapers to achieve a  LEED Gold certification, the most noticeable  

transformations for visitors will be found  throughout the Observatory Experience.

The Empire State Building has remained one of  New York's most popular attractions with over  

four million annual visitors - and the  new upgrades help it retain that position.

Greeted by a new entrance lobby,  visitors will now make their way  

through an interactive museum to the  first viewing level on the 80th Floor.

This level gives visitors their first glance of  

the views they'll have on the  famous 86th Floor Observatory.

From there, a custom-built glass elevator by  Otis takes visitors to the renovated 102nd-Floor,  

giving them a never-before-seen look at the  inside of the building's mast on the way.

Seeking to make the 16-storey ride an experience  in itself, Otis used its innovative Gen2 elevator  

system, eliminating the need for a lift motor  room and other mechanical equipment within the  

confined space of the mast structure and giving  visitors unobstructed views as they travel.

Using less energy than roped systems  and improving passenger comfort with  

a steel-reinforced polyurethane belt that  cuts noise and vibration, the Gen2's small  

footprint makes it an ideal choice for the  confined spaces within unique structures.

The Gen2 system removed the need for a basement  motor room at Seoul's 555-metre Lotte World Tower,  

transports guests at the Armani Hotel and  penthouses inside the Burj Khalifa – the world's  

current tallest building - and even takes visitors  to the base of Brazil's Christ the Redeemer statue  

- another iconic landmark that was completed  in the same year as the Empire State Building.

In fact, as maximising space has become a  common goal in buildings around the world,  

the Gen2 system has become the most  popular elevator in Otis' history,  

despite only coming to the market in 2000.

To date, more than a million units have been sold.

From its base to its summit, the Empire State  Building has undergone one of the largest  

modernisation programs of any skyscraper to date;  setting new benchmarks for energy efficiency while  

retaining the historic style that has made  it one of the world's most famous buildings.

While the word “iconic” may  perhaps be overused these days,  

the Empire State Building is  truly deserving of the adjective;  

a timeless symbol of New York City that  can now endure long into the future.

This video was made possible by  Otis. To learn more about the  

Otis Gen2 elevator and its mechanical to  digital evolution and what's to come next,  

click the link below - and as always if you  enjoyed this video and would like to get  

more from the definitive video channel  for construction, subscribe to The B1M.