Place Facts About Engineering

The 426 escalators in the London Underground cover a distance every week equivalent to traveling around the world more than twice.

There are 2,500,000 rivets in the Eiffel Tower.

Samsung is also a full time weapons manufacturer.

The Statue of Liberty's torch arm sits 18 inches from where it was designed to be. Before her 100th birthday, engineers found it swaying in strong winds, with a spike of her crown threatening to pierce it. Crews turned the spike away and swapped almost every iron bar holding her copper skin while she stood. They never moved the arm, or her head, which still sits 2 feet off-center.

Joseph Strauss spent $130,000 on a safety net under the Golden Gate Bridge during construction - the most expensive safety device ever built for a bridge at the time. It saved 19 men who fell from the deck. Those survivors formed a club: the Halfway to Hell Club.

The floor of Hoover Dam's monument plaza is a celestial map. Sculptor Oskar J.W. Hansen embedded 209 brass discs into the terrazzo, each marking a star or planet visible on September 30, 1935 - the night FDR dedicated the dam. It took 200,000 astronomical calculations. If every historical record vanished, a future civilization could read that floor and calculate exactly when Hoover Dam was dedicated.

Abu Simbel's colossal temples were carved by Ramesses II 3,200 years ago. When Egypt's Aswan Dam threatened to flood them, Egypt and 48 nations raised $40 million. Engineers sliced the temples into 1,000+ blocks - some weighing 30 tons - then rebuilt everything 65 meters higher. The solar alignment still works.

Cape Hatteras Lighthouse is the tallest brick lighthouse in America, nearly 200 feet tall. At its closest, the Atlantic had come within 120 feet of its base. So engineers lifted the entire tower onto steel rails. They rolled it more than half a mile inland, five feet at a time. It took 23 days. Not one new crack formed in the century-old brick.

Galveston jacked its entire city into the sky. After the 1900 hurricane killed an estimated 8,000 people, crews put 2,000+ buildings on hand-cranked jackscrews, raising some up to 17 feet, including this 3,000-ton church. The 1915 hurricane killed only 11.

Sears Tower's Ledge lets tourists step onto glass floors 1,353 feet above Chicago's sidewalks. Each box weighs 1,500 pounds, built from three layers of half-inch glass. It's engineered to hold 10,000 pounds. No one leans out a window to clean it. A motor pulls the whole box back on rails, straight into the building, then slides back out over the drop. The boxes are still open every day, right now.

Duluth's Aerial Lift Bridge doesn't tilt or swing. Its whole 386-foot span shoots 126 feet straight up in a minute, opening 141 feet of clearance for 1,000-foot ships. Built as a transporter ferry in 1905, it became a lift bridge in 1929. Ships blast a long-short-short Captain's Salute; the bridge answers back. It still does this for almost 900 ships a year, carrying 35 million tons of cargo.

Hoover Dam's spillway tunnel tore itself open in 1941. After a gate dropped without warning, water roaring down the Arizona spillway gouged a hole about 115 feet long, 30 feet wide and 45 feet deep, through the concrete and into the rock. The 1983 flood damaged the tunnels again. Today Lake Mead sits so low that the dam's two spillways stand bone dry, about 165 feet above the water.

A London skyscraper accidentally became a giant curved mirror. Its glass facade focused sunlight into a beam so intense it melted a parked Jaguar, scorched a shop, and let a reporter fry an egg on the pavement. The architect had built the same flaw in Las Vegas years earlier.

The Gateway Arch was built as two separate legs measured to meet precisely at the top. On October 28, 1965, the morning sun expanded the south leg. The last piece would not fit. Workers ran fire hoses to the top and soaked the steel until it shrank. Hydraulic jacks applied 450 tons of force, and the final section slid in.

The Leaning Tower of Pisa closed in 1990 for the first time in 800 years. Engineers warned it was close to collapse. Over 11 years, they drilled beneath the north side and extracted soil. The tower settled back by 44 centimeters. It reopened in December 2001. Experts say it is now safe for at least 300 more years.

William Van Alen hid a 185-foot steel spire inside the Chrysler Building's own crown, assembled in secret. His rival H. Craig Severance had designed 40 Wall Street two feet taller - thinking he'd win. Van Alen raised the hidden spire through the roof in 90 minutes on October 23, 1929. The Chrysler Building jumped to 1,046 feet, the first skyscraper to top 1,000 feet. It held the record for 11 months.