The Skyscraper Museum, located in New York City in the United States, has been the only museum of its kind in the world since opening on May 1, 1997. As the name suggests, the museum focuses on high-rise buildings as "objects of design, products of technology, sites of construction, investments in real estate, and places of work and residence." The original site of the museum was located very close to the World Trade Center. After the September 11, 2001 attacks, the museum was forced to close temporarily as its space was commandeered as an emergency information center. In March 2004, the museum reopened in its new permanent home in the neighbourhood of Battery Park City at the southern tip of Manhattan. The new site was designed by Roger Duffy of Skidmore, Owings & Merrill, working pro bono. The museum features stainless steel floors and exhibition areas meant to give the feeling of standing 40 stories in the air over a Manhattan street. On September 6, 2006, the museum opened an exhibit on the construction and history of the World Trade Center. The exhibit includes the original architectural/engineering model of the World Trade Center. On June 24, 2009, the museum opened China Prophecy: Shanghai, a multi-media exhibition that examines Shanghai's evolving identity as a skyscraper metropolis. Featuring models of the major iconic structures, including Jin Mao, Tomorrow Square, Shanghai World Financial Center, and the new super-tall Shanghai Tower, as well as computer animations, film, drawings, and historic and contemporary photography of the city, the exhibition combines an in-depth look at the new generation of towers with an overview of the sweeping transformation of the city’s traditional low-rise landscape into a city of towers. Besides in-house exhibitions, the museum also sponsors external shows and programs at various locations in the city. Additionally, the museum offers a unique virtual gallery through its website, which is an advanced 3-D archive of Manhattan skyscrapers. Carol Willis, a professor of urban studies and planning at Columbia University and architectural historian, is the founding director of the Skyscraper Museum.