Willis Tower

The Willis Tower is a very tall building.

It is in Chicago. It has many floors. Some say it has 110 floors.

The building looks like nine square tubes. These tubes are bunched together. This shape helps it stand tall. The outside is made of black glass.

Many people visit the Skydeck. This is a high place to see. It is a popular spot for visitors. You can see far away from there.

People can also see the tower from far away. It is very easy to spot. It is a famous part of the city.

The Willis Tower is a giant skyscraper in Chicago.

It is very tall. It has 110 stories. For nearly 25 years, it was the tallest building in the world.

Architect Bruce Graham and engineer Fazlur Rahman Khan designed it. They used a special way to build it. They made nine square tubes. These tubes are bunched together in a group.

This shape helps the tower stay strong. The outside is made of black glass and aluminum.

Many people visit the Skydeck. This is an observation deck, or a high place to look out. It is the highest in the United States.

You can look through glass boxes at the view. More than 1.7 million people visit each year.

People used to call it the Sears Tower. A large store called Sears used the building for many years. Now, the Willis Group uses the name. Many people in Chicago still use the old name. The tower is so big that you can see it from far away.

The Willis Tower is a massive skyscraper located in the Loop of Chicago, Illinois.

It stands 110 stories tall and reaches high into the sky. For nearly 25 years, it held the title of the tallest building in the world.

Today, it is the third-tallest building in the Western Hemisphere. It is also the 26th-tallest building in the whole world.

Many people visit the Skydeck, which is the highest observation deck in the United States.

Over 1.7 million people visit this famous spot every year. Because it is so tall, you can see the tower from a very long distance.

Architect Bruce Graham and engineer Fazlur Rahman Khan designed the building's unique shape.

They used a method involving nine square "tubes" grouped together in a 3x3 matrix.

Seven of these tubes set back at the upper floors. This design creates a distinctive look with tapering floor plates.

The outside of the tower is made of black glass and anodized aluminum.

This clever design allowed the building to be both strong and useful for many different people. The lower floors provide large spaces, while the upper floors offer smaller offices.

Sears, Roebuck & Co. wanted a new home for its many employees.

By 1969, Sears was the largest retailer in the world with 350,000 employees. They needed a large headquarters to hold thousands of workers.

They chose a site in the Loop bounded by Franklin Street and Adams Street.

To build there, the company had to buy 15 buildings from 100 different owners.

They even paid the city of Chicago $2.7 million to close one street.

This helped create the space needed for such a huge project.

Construction on the foundation began in August 1970.

Workers had to dig very deep and remove a huge amount of dirt.

They built a strong wall using concrete and reinforced steel to hold the ground.

At one point, 2,000 workers were employed on the project.

To work faster, they even built a concrete plant right in the basement.

This allowed them to pour a new concrete floor every single day.

The first steel beam was installed during a ceremony in June 1971.

People have many different names for this famous landmark.

Most people know it as the Willis Tower today.

This name came from a 2009 lease with the Willis Group.

However, it was known as the Sears Tower for a very long time.

Many local residents in Chicago still call it by its old name.

The building is also a star in many movies and TV shows.

It remains a symbol of the city and a place of wonder.

The Willis Tower is a massive skyscraper located in the Loop of Chicago, Illinois.

It stands 110 stories tall, though some count the floors differently. Standard methods count 108 stories. The owners count the main roof as 109 and the mechanical penthouse roof as 110. For nearly 25 years, it held the title of the world's tallest building.

Today, it remains the third-tallest building in the Western Hemisphere. It is also ranked as the 26th-tallest building globally.

The tower is a major tourist destination. More than 1.7 million people visit the Skydeck every year. This is the highest observation deck in the United States.

Architect Bruce Graham and engineer Fazlur Rahman Khan designed the tower's unique structure.

They used a method called the bundled tube structure. This design consists of nine square "tubes" arranged in a 3x3 matrix.

Seven of these tubes set back at the upper floors. This creates a series of setbacks with tapering floor plates.

The exterior facade is made of black glass and anodized aluminum. This design allowed the building to serve many different needs. The lower floors offer large areas for big companies. The upper floors provide smaller, conventional office spaces for other tenants.

Sears, Roebuck & Co. originally commissioned the building for its headquarters.

By 1969, Sears was the largest retailer in the world. They had about 350,000 employees at that time. They needed a way to consolidate thousands of workers. These employees were previously spread across many offices in the Chicago area. The company chose a site in the Loop. This site is bounded by Franklin Street, Jackson Boulevard, Wacker Drive, and Adams Street.

To prepare the site, Sears purchased 15 buildings from 100 different owners. They also paid the city of Chicago $2.7 million to close one block of Quincy Street.

Construction on the foundation began in August 1970.

Workers excavated the lot to a depth of 100 feet. They removed a massive amount of dirt from the site. To prevent the ground from collapsing, they built a slurry wall. This wall was made of concrete and reinforced steel. Workers used caissons to drill 201 holes into the ground.

The Diesel Construction Company served as the general contractor. At the height of construction, the project employed 2,000 workers. To speed up the work, a concrete plant was built in the basement. This allowed workers to pour one-third of a concrete floor every day.

As the tower rose, it caused a controversy regarding broadcast signals.

Some residents feared the height would disrupt television broadcasts. Estimates suggested it could obstruct signals for 15 percent of Chicagoans. It might also cause "double images" for another 20 percent of viewers. Several villages, including Skokie, filed lawsuits to limit the building's height. They wanted to cap the tower at 67 stories. However, the courts eventually dismissed these suits. Judges ruled that viewers did not have a right to reception without interference. The Federal Aviation Administration also approved antennas for the roof.

The tower has undergone several name changes over the years.

It was known as the Sears Tower from its construction until 2009. This was because Sears was the original primary tenant. In 2009, the naming rights were included in a lease with the Willis Group. Now, it is officially called the Willis Tower.

Despite the official name, many local residents still use the old name. The building remains a famous part of the Chicago skyline. It has appeared in many films and television shows set in the city.

Today, the building serves many different large companies.

United Airlines is the largest tenant, occupying 16 floors. Other major tenants include Morgan Stanley and Willis Towers Watson. The base of the tower contains a retail complex called the Catalog.

Visitors can experience the height through the Skydeck. Some can even look through glass-bottom skyboxes on the west facade.

This allows people to see the streets far below. The tower remains a vital part of Chicago's business and tourism.