http://en.wikipedia.org/wiki/Geography_of_Washington,_D.C.#B...To preserve the grandeur of the National Mall, the White House, the Capitol, and various other key locations, the entire city is subject to strict building height limits. This limitation was placed in effect just prior to the 20th century when government officials realized that structural steel "skyscrapers" could overwhelm the city. In 1899, Congress enacted a height limit for the District prohibiting private buildings from rising more than 130 feet. Contrary to popular belief, no law has ever restricted buildings to the height of the United States Capitol or Washington Monument.[20][21]
A revised height law in 1910 did away with that fixed maximum. The newer legislation, still in effect today, states that no new building may be more than 20 feet taller than the width of the street in front of it.[22] The current law is codified as D.C. CODE ANN. § 6-601.05. Thus, Washington has a relatively modest skyline in comparison to the majority of American cities. However the District is ringed by high-rise buildings in many nearby suburbs like Arlington, Silver Spring, and Bethesda.