Skyscrapers

		One famous skyscraper of Pittsburgh is the gothic style PPG Place. It's architect, John Burgee architectural firm and Phillip Johnson, were not from Pittsburgh but New York. This six hundred eighty foot tower is the tallest of six PPG
		Buildings. It has eight pinnacles, or lofty peaks to give weight. if you count all the pinnacles of all the buildings you would find there are two hundred thirty one in all. The whole outer building is covered in silver-gray reflective glass.
	One of the most famous skyscrapers of the United States is New York's Empire State Building. It was built with crossing moment frames and stiff x-bracer in the walls. The Empire State Building is about one thousand two hundred feet tall. The building used sixty thousand tons of steel to support
	the two million feet of floor space. They used over thirty-five thousand workers to build the building. Though it was built in little over one year it is very solid. Even when hit by a Air force B-25 in 1945, the building still stands.
		The second and third tallest building in the world are in the city of Kuala Lumpury, Malaysia. They are the Petronas Towers. They are twin towers and have a sky bridge on the forty-second and forty-first floors. It took three years to complete, about two floors a week. On the top of
		these buildings are huge lightning rods to protect from the frequent lightning strikes. The petrona is made mostly of steel and concrete. It was going to be the tallest building but never was because it took so long to build. It stands one thousand five hundred feet tall.
	Sears Tower, Chicago is the tallest building in United States. This building "steps back" or the building's walls go back making the top smaller than the bottom. Its steel bars are spaced fifteen feet apart and form nine , seventy-five by fifteen feet squares. To build this building in only three years they had to use three cranes to hoist "trees" or
	twenty-five foot tall columns with half beams already attached. The finished building is about one thousand five hundred feet tall, used seventy six thousand tons of steel supports, and has four point one million square feet of floor space. Though the structure is no longer owned by the company Sears this gigantic office building has kept it original name.
		The Us Steel building, formally known as the USX tower, is the tallest building in all of Pittsburgh. It, like PPG Place, was designed by New Yorkers Harrison and Abramoviz. It was built in 1970 and is eight hundred forty feet high. Its main feature is its exposed steel bars that make up the structure.