The unlimited beauty of urban architecture in Frankfurt/Main, beautifully captured and presented...03/2010...Simply be and enjoy...:)
The word "skyscraper" originally was a nautical term referring to a small triangular sail set above the skysail on a sailing ship. The term was first applied to buildings in the late 19th century as a result of public amazement at the tall buildings being built in Chicago and New York City. The first skyscraper was for many years thought to be the Home Insurance Building built in in Chicago Illinois in 1885. More recent evidence points to New York's Equitable Life Assurance Building built in 1870 preceeding the Chicago building by 15 years and was the first office building built using a skeletal frame. 
The structural definition of the word skyscraper was refined later by architectural historians, based on engineering developments of the 1880s that had enabled construction of tall multi-storey buildings. This definition was based on the steel skeleton—-as opposed to constructions of load-bearing masonry, which passed their practical limit in 1891 with Chicago's Monadnock Building. Philadelphia's City Hall, completed in 1901, still holds claim as the world's tallest load-bearing masonry structure at 167 m (548 ft). The steel frame developed in stages of increasing self-sufficiency, with several buildings in Chicago and New York advancing the technology that allowed the steel frame to carry a building on its own. Today, however, many of the tallest skyscrapers are built almost entirely with reinforced concrete. Pumps and storage tanks maintain water pressure at the top of skyscrapers.
A loose convention in the United States and Europe now draws the lower limit of a skyscraper at 150 meters (~500 ft).[verification needed] A skyscraper taller than 300 meters (~1000 ft) may be referred to as supertall.[by whom?] Shorter buildings are still sometimes referred to as skyscrapers if they appear to dominate their surroundings.[by whom?]
The somewhat arbitrary term skyscraper should not be confused with the also ill-defined term high-rise. The Emporis Standards Committee defines a high-rise building as "a multi-story structure between 35-100 meters tall, or a building of unknown height from 12-39 floors" and a skyscraper as "a multi-story building whose architectural height is at least 100 meters." Some structural engineers define a highrise as any vertical construction for which wind is a more significant load factor than earthquake or weight. Note that this criterion fits not only high rises but some other tall structures, such as towers.
The word skyscraper often carries a connotation of pride and achievement. The skyscraper, in name and social function, is a modern expression of the age-old symbol of the world center or axis mundi: a pillar that connects earth to heaven and the four compass directions to one another.