that instantly reduced the building to rubble. The late 19th century saw the erection of—and ultimately the need to demolish—the first skyscrapers, which had more complicated structures, allowing greater heights. This led to other considerations in the explosive demolition of buildings, such as worker and spectator safety and limiting collateral damage. Benefiting from the availability of dynamite, a high-velocity explosive based on a stabilized form of nitroglycerine, and borrowing from techniques used in rock-blasting, such as staggered detonation of several small charges, the process of building implosion gradually became more efficient. Following World War II, European demolition experts, faced with huge reconstruction projects in dense urban areas, gathered practical knowledge and experience for bringing down large structures without harming adjacent properties. This led to the emergence of a demolition industry that grew and matured during the latter half of the twentieth century. At the same time, the development of more efficient high-velocity explosives, such as RDX, and non-electrical firing systems combined to make this a period of time in which the building implosion technique was extensively used. Meanwhile, public interest in the spectacle of controlled building explosion also grew. The October 1994 demolition of the Sears Merchandise Center in Philadelphia, Pennsylvania drew a cheering crowd of 50,000, as well as protesters, bands, and street vendors selling building implosion memorabilia. Evolution in the mastery of controlled demolition led to the world record demolition of the Seattle Kingdome on March 26, 2000. In 1997, the Royal Canberra Hospital in Canberra, Australia, was demolished. The main building did not fully disintegrate and had to be manually demolished. The explosion during the initial demolition attempt was not contained on the site and large pieces of debris were projected towards spectators away, in a location considered safe for viewing. A twelve-year-old girl was killed instantly, and nine others were injured. Large fragments of masonry and metal were found from the demolition site. On October 24, 1998, the J. L. Hudson Department Store and Addition in Detroit, Michigan became the tallest, and the largest, building ever imploded. On December 13, 2009, an unfinished 31-story condominium tower, known as the Ocean Tower, was imploded in South Padre Island, Texas. Construction on the new tower had begun in 2006, but it had been sinking unevenly during construction, which halted in 2008, and could not be saved. It is believed to be one of the tallest reinforced concrete structures