Twenty years ago, the World Trade Center and its Twin Towers were attacked on the morning of 11 September 2001 by terrorists who intentionally flew two airplanes into the towers and caused them to collapse. As the 20th anniversary of 9/11 approaches, this is a time for the world to commemorate the families, friends, and colleagues who perished that day. It is also an opportunity to educate new generations about what happened, by using scientific evidence and rejecting the increasing influences of disinformation and conspiracy theories in society, including those surrounding 9/11.

As we look back and reflect on the last 20 years, the Council on Tall Buildings and Urban Habitat (CTBUH)—an international authority on tall buildings that conducts research and education on vertical growth and sustainable and healthy cities—is greatly concerned about the increasing influence of conspiracy theories and the rejection of science in society.

9/11 has become one of many examples where conspiracy theories have thrived—even though professional experts in structural design, material properties, building demolition, fire resistance, and structural monitoring have and continue to dismiss false information that controlled demolition played a part in the collapse of the towers. In addition to the immense amount of rigorous and credible scientific research as to the reasons why and how the Twin Towers collapsed, validated by technical and scientific experts, there is a persistent lack of evidence for the validity of the conspiracies.

CTBUH represents hundreds of firms responsible for the design, engineering, construction, and safety of skyscrapers. We reject the promulgation of false information and affirm our support of the scientific evidence about the cause of the World Trade Center collapse. We encourage all who believe in scientific evidence to take this somber anniversary as an opportunity to educate new generations that the proven cause of the World Trade Center collapse was the direct impact of the airplanes and uncontrolled fires.