Pentagon vs Washington Monument

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The Pentagon is the headquarters building of the United States Department of Defense.

As a symbol of the U.S. military, the phrase The Pentagon is also often used as a metonym for the Department of Defense and its leadership. Located in Arlington County, Virginia, across the Potomac River from Washington, D.C., the building was designed by American architect George Bergstrom and constructed by contractor John McShain. Ground was broken on 11 September 1941, and the building was dedicated on 15 January 1943. General Brehon Somervell supplied the important motivating power behind the project; Colonel Leslie Groves was responsible for overseeing the project for the U.S. Army. The Pentagon is the world's largest office building, with about 6,500,000 sq feet (600,000 m2) of space, of which 3,700,000 sq feet (340,000 m2) are used as offices. Some 23,000 military and civilian employees, and another 3,000 non-defense support employees, work in the Pentagon.



It has five sides, five floors above ground, two basement levels, and five ring corridors per floor with a total of 17.5 mi (28.2 km) of corridors. The fundamental five-acre (20,000 m2) pentagonal plaza is nicknamed'ground zero' on the presumption that it would be a prime target in a nuclear war.On 11 September 2001, exactly 60 years after the building's construction began, American Airlines Flight 77 was hijacked and flown into the western side of the building, killing 189 people (59 victims and the five terrorists on board the airliner, as well as 125 victims in the building), according to the 9/11 Commission Report. It was the first major foreign attack on Washington's governmental facilities since the town was burned by the British during the War of 1812. The Pentagon is listed on the National Register of Historic Places and is a National Historic Landmark.

Source: Wikipedia

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The Washington Monument is an obelisk on the National Mall in Washington, D.C., Constructed to commemorate George Washington, once commander-in-chief of the Continental Army (1775--1784) in the American Revolutionary War and the first President of the United States (1789--1797).

Located almost due east of the Reflecting Pool and the Lincoln Memorial, the monument, made of marble, granite, and bluestone gneiss, is both the world's tallest predominantly stone structure and the world's tallest obelisk, standing 554 ft 7 11?32 inches (169.046 m) tall according to the U.S. National Geodetic Survey (measured 2013--14) or 555 ft 5 1?8 inches (169.294 m) tall according to the National Park Service (measured 1884). It's the tallest monumental column in the world if all are measured above their pedestrian entrances. Overtaking the Cologne Cathedral, it was the tallest structure in the world between 1884 and 1889, and it had been overtaken by the Eiffel Tower in Paris. Construction of the monument began in 1848 and was stopped for a period of 23 years, from 1854 to 1877 because of a lack of capital, a battle for control within the Washington National Monument Society, and the American Civil War. Although the stone structure was completed in 1884, inner ironwork, the knoll, and installation of memorial stones weren't completed until 1888. A difference in shading of the marble, visible approximately 150 ft (46 m) or 27% up, shows where construction was halted and later resumed with marble from a different source. The original design was by Robert Mills (1781--1855) of South Carolina, but he did not include his proposed colonnade because of a lack of funds, proceeding only with a bare obelisk. The cornerstone was laid on July 4, 1848; the first stone was set atop the unfinished stump on August 7, 1880; the capstone was set on December 6, 1884; the completed monument was dedicated on February 21, 1885; and officially opened October 9, 1888. The Washington Monument is a hollow Egyptian style stone obelisk with a 500-foot (152.4 m) tall column surmounted by a 55-foot (16.8 m) tall pyramidion. Its walls are 15 feet (4.6 m) thick at its base and 1 1?2 ft (0.46 m) thick at their top. The marble pyramidion has thin walls only 7 inches (18 cm) thick supported by six arches, two between opposite walls which cross at the center of the pyramidion and four smaller corner arches. The cover of the pyramidion is a large marble capstone with a little aluminum pyramid at its apex with inscriptions on all four sides. The lowest 150 ft (45.7 m) of the walls, constructed during the initial phase 1848--1854, are composed of a heap of bluestone gneiss rubble stones (not completed stones) held together by a large amount of mortar using a facade of semi-finished marble stones about 1 1?4 ft (0.4 m) thick. The upper 350 ft (106.7 m) of the walls, constructed during the next stage 1880--1884, are composed of finished marble surface stones, half of which project to the walls, partially backed by completed granite stones.The interior is occupied by iron stairs that spiral up the walls, with an elevator at the center, each supported by four iron columns, which do not encourage the stone structure. The stairs contain fifty sections, most on the north and south walls, with many long landings extending between them across the east and west walls. These landings allowed many inscribed memorial stones of different materials and sizes to be easily viewed while the stairs were available (until 1976), plus one memorial stone between stairs which is difficult to view. The pyramidion has eight observation windows, two per side, and eight red aircraft warning lights, 2 p