7 Wonders of the Modern World
People have put together many lists of the Seven Ancient Wonders of the World. But this "seven wonders" list celebrates monumental engineering and construction feats of the 20th century. It was chosen by the American Society of Civil Engineers in 1994.
Built by Brazil and Paraguay on the Paraná River, the Itaipu dam is the world's largest hydroelectric power plant. Completed in 1991, it took 16 years to build this series of dams whose length totals 7,744 m. It used 15 times more concrete than the Channel Tunnel, which connects England and France.
From 1976 to 2007 (when it was surpassed by the Burj Dubai), the CN Tower was the world's tallest freestanding structure. It looms about one-third of a mile high (1,815 ft) above Toronto, Canada. A glass floor on the observation deck lets you look 1,122 ft (342 m) down to the ground.
It took 34 years to create this 50-mile-long canal across the Isthmus of Panama. The amount of digging required and the size of its locks helped make it the most expensive project in American history at that time—and the most deadly: About 80,000 people died (most from disease) during construction of the Panama Canal.
Known as the Chunnel, the Channel Tunnel links France and England. It is 31 mi (9 m) long, and 23 of those miles are 150 ft (45.7 m) beneath the seabed of the English Channel. High-speed trains whiz through its side-by-side tubes.
Netherlands North Sea Protection Works
Because the Netherlands is below sea level, a series of dams, floodgates, and surge barriers have been built to keep the sea from flooding the country during storms. The biggest part of the Netherlands North Sea Protection Works was a two-mile-long moveable surge barrier across an estuary finished in 1986. It is made of 65 concrete piers each weighing 18,000 tons. It has been said that the project is nearly equal in scale to the Great Wall of China.
Golden Gate Bridge
Connecting San Francisco and Marin County in 1937, for many years the Golden Gate Bridge was the longest suspension bridge in world. Experts thought that winds, ocean currents, and fog would make it impossible to build. It took about four years to complete the beautiful 1.2-mile-long (1.9 km) bridge. It is held by 80,000 mi (128,747 km) worth of steel wire, and the cables that link the two towers are 36.5 (92.7 cm) inches in diameter—the biggest ever made.