Ground Zero is a term used to describe the point on the surface of the Earth at the centre of, or closest to, a major explosion. The term originated with the nuclear bombings of Hiroshima and Nagasaki. In New York it is used to describe the site on which the World Trade Center stood.
The original clean-up of the site was completed in May 2002. Architect Daniel Libeskind won a competition in 2003 to redesign the site; currently only one building has been completed, but other towers and buildings of the new World Trade Center are under construction. The site will feature a memorial, consisting of two square pools where the towers used to stand and a monument bearing the names of the dead, scheduled to open on 11th September 2011, the 10 year anniversary.
Visitors to Ground Zero can explore a museum dedicated to 9/11. Every year the Tribute in Light takes places on 11th September: two beams of light are projected upwards from the site, commemorating the two towers.