How tall is the World Trade Center Twin Towers?

How tall the Twin Towers were

The original World Trade Center in Lower Manhattan was built around two almost identical 110-story towers. The North Tower (1 WTC) stood 417 m (1,368 ft) to its roof, and the South Tower (2 WTC) stood 415 m (1,362 ft). This page uses the North Tower's 417 m roof height as the headline figure, because it is the taller tower's official building height.

Many sources give a much bigger number, around 527–530 m (about 1,730 ft). That is the North Tower including its broadcast antenna, a 1978–79 addition that carried television and radio transmitters. Skyscraper rankings from the Council on Tall Buildings and Urban Habitat (CTBUH) exclude antennas from a building's architectural height. CTBUH treats them as equipment that can be put up or taken down. Spires count because they are part of the design. So the official comparison height of the North Tower stays at its roofline.

The difference between the two towers was only about 2 m, too small to see from the street. To tell them apart, people looked for the antenna on the North Tower and the rooftop observation deck on the South Tower.

Design: Yamasaki's slender tubes

The complex was commissioned by the Port Authority of New York and New Jersey, with Minoru Yamasaki as lead architect. Leslie Robertson of the firm Worthington, Skilling, Helle & Jackson was one of the chief structural engineers. Their design used a then-new system called the framed tube. Instead of relying mainly on a forest of interior columns, each tower's outer walls were a dense grid of closely spaced steel columns. The facade itself took most of the wind load, and a central core carried much of the gravity load.

NIST's later investigation describes the floors spanning between the core and the perimeter as composite steel trusses topped with concrete slabs, leaving about 31,000 sq ft of open office space around the core on a typical floor. That column-free space was one of the main selling points to tenants.

The narrow vertical windows set between the perimeter columns gave the towers their pinstriped look. They also made the buildings look taller and thinner than their roughly 6.6-to-1 proportion of height to width.

Moving people up 417 m

A 110-story building needs more elevator shafts than it can easily fit. The designers solved this with sky lobbies on the 44th and 78th floors. Express elevators took people to a sky lobby, where they switched to local elevators that served a smaller band of floors. Like a subway with express and local trains, the system let several local elevators share each shaft, which freed up floor space at every level.

Construction timeline and the world height record

When the North Tower topped out in December 1970, it took the world's-tallest-building title from the Empire State Building, which had held it since 1931. The record didn't last long. Chicago's Sears Tower was finished in 1973 and opened in 1974. CTBUH now gives it an architectural height of 442.1 m, about 25 m above the North Tower's roof. The Willis Tower, as it has been called since 2009, kept the title until 1998.

The towers still had a lasting effect on the skyline. They were the first buildings to pass the Empire State Building's roof in four decades. For almost 30 years, from the early 1970s to 2001, they were the twin landmarks that photos of Lower Manhattan were framed around.

Life at the top: Top of the World and Windows on the World

The public could get very high in the old World Trade Center. The South Tower's Top of the World observation deck was indoors on the 107th floor, at about 400 m (1,310 ft). In good weather visitors could take escalators up to an outdoor platform on the roof at about 420 m (1,377 ft). That rooftop deck was among the highest open-air viewing platforms anywhere at the time, and it stood slightly above the tower's own 415 m roofline because it was raised on the roof structure.

In the North Tower, the restaurant Windows on the World occupied the 106th and 107th floors. Its tables sat higher above the ground than the roof of the Empire State Building.

In 1974 the French high-wire artist Philippe Petit strung a cable across the roughly 43 m (140 ft) gap between the roofs and walked back and forth on it for about 45 minutes. It remains one of the most famous stunts ever performed at height.

September 11, 2001

On the morning of September 11, 2001, hijacked aircraft were flown into both towers. According to NIST, American Airlines Flight 11 struck the North Tower at 8:46 a.m. and United Airlines Flight 175 struck the South Tower at 9:02 a.m. The South Tower collapsed at 9:58 a.m. and the North Tower at 10:28 a.m. NIST counts 2,735 people killed in the attacks on the towers, including 2,184 people who were inside the buildings, plus the aircraft occupants and emergency responders who died there.

The towers had already been attacked once. On February 26, 1993, a truck bomb was set off in the underground garage of the North Tower. The bombing killed six people, though the structure survived.

Today the National September 11 Memorial stands where the towers stood. Its two reflecting pools, each nearly an acre, are set into the towers' footprints. The water falls about 30 ft into each square basin and then drops another 20 ft into a central void. Bronze parapets around the pools carry the names of the 2,983 people killed in the 2001 attacks and the 1993 bombing.

Comparisons: the Twin Towers next to other skyscrapers

The North Tower's 417 m roof is useful as a benchmark because it falls between the classic skyscrapers of the twentieth century and today's supertalls. The figures below use this site's landmark data. You can stack them side by side in the 3D comparison tool.

The Burj Khalifa comparison shows how quickly heights have grown. Two Twin Towers stacked end to end (834 m) would be only about 6 m taller than the Dubai tower's architectural top.

One World Trade Center and the 1,776-foot echo

The main replacement tower, One World Trade Center, was completed in 2014 just northwest of the old towers. CTBUH lists it at 541.3 m (1,776 ft) to its architectural top, a height chosen for the year of the Declaration of Independence. That counts the tower's spire, which CTBUH accepted as an architectural element. Its highest occupied floor is 386.5 m, about 30 m below the North Tower's roof. And the One World Observatory, on levels 100–102, sits lower than the old Top of the World deck.

So the answer to "Is One World Trade Center taller than the Twin Towers?" depends on the measure:

• Official architectural height: yes, by about 124 m.
• Height to tip: yes, but only by about 16–19 m over the North Tower's antenna.
• Roof and occupied floors: no. The original towers' roofs and top floors were higher.

Why sources disagree on the numbers

Because the towers no longer stand, nobody can re-survey them, and published figures come from drawings, Port Authority records and surveys made while they stood. That explains most of the small differences you'll find.

Roof height. The 417 m and 415 m figures are the standard values. You'll sometimes see 1,368 ft and 1,362 ft rounded to 1,370 ft and 1,360 ft, or converted to meters with different rounding, which produces values such as 416.7 m or 417.0 m for the same roof.

Antenna height. Figures for the North Tower's tip range from about 526 m to 530 m. Some sources measure to the top of the antenna mast itself, others to the highest piece of equipment or lightning protection on it. The mast was also refitted while it stood. So "about 527–530 m" is the honest range, and it is the range this site's data records.

Floor counts. Both towers are listed at 110 stories above ground, but several of those were mechanical floors housing equipment rather than offices, and the complex also had several basement levels. Whether a source counts mechanical and basement levels changes the total it gives, so check the counting convention before comparing floor numbers between buildings.

Which tower was "the tallest". The North Tower topped out first, in December 1970, and was always the taller of the two by about 2 m. When people say the World Trade Center was the world's tallest building, they mean the North Tower. Histories of the world's-tallest title list it as the record holder between the Empire State Building and the Sears Tower.

Present-day rankings list only standing buildings, so the Twin Towers no longer appear in current "world's tallest" tables. They are still recorded in the history of the title, which is why lists of past record holders include them with their 417 m roof height.

Remembering their scale

People who never saw the towers often find their size hard to picture today. Here are some ways to put 417 m in perspective:

• At street level, each tower's facade was about 63 m wide. A tower could almost have fit inside a soccer pitch, yet it was more than six times taller than it was wide.
• The Empire State Building's roof would have reached only about the North Tower's 100th floor.
• A 6-foot (183 cm) person would have to be stacked about 228 times to reach the roofline.

To compare the original towers with other buildings around the world, see our tallest lists or browse every structure on the landmarks hub.