One WTC in construction  ©2012 MacKinnon

On the day of the attacks, New York City mayor Rudy Giuliani proclaimed, "We will rebuild. We're going to come out of this stronger than before, politically stronger, economically stronger. The skyline will be made whole again."

The damaged section of the Pentagon was rebuilt and occupied within a year of the attacks. The temporary World Trade Center PATH station opened in late 2003 and construction of the new 7 World Trade Center was completed in 2006. Work on rebuilding the main World Trade Center site was delayed until late 2006 when leaseholder Larry Silverstein and the Port Authority of New York and New Jersey agreed on financing. One World Trade Center is currently under construction at the site and at 1,776 ft (541 m) upon completion in 2013, will become the tallest building in North America.

On the World Trade Center site, three more office towers are expected to be built one block east of where the original towers stood. Construction has begun on all three of these towers; they are expected to be completed after One World Trade Center.