To stand alongside the Seven Wonders of the Ancient World, there are now Seven Wonders of the Modern World - the greatest civil engineering achievements of the 20th century.
The American Society of Civil Engineers joined with Popular Mechanics, the Hearst publication, to choose these achievements, according to an article in the magazine by science technology editor Gregory T. Pope. They were selected from nominations by engineering societies around the world and winnowed by an international panel of advisers.The wonders of the ancient world, listed by the Greek historian Antipater in 240 B.C., were the pyramids of Egypt, the hanging gardens of Babylon, the temple of Artemis at Ephesus, Phidias' statue of Zeus at Olympia, the Mausoleum at Halicarnassus, the Colossus of Rhodes and the Pharos at Alexandria.
The Seven Wonders of the Modern World are:
- Itaipu Dam, the world's largest hydroelectric plant. The 5-mile-wide, $18 million dam spans the Parana River at the Brazil-Paraguay border. The marvel of Itaipu is its half-mile-long powerhouse, which puts out 12,600 megawatts - enough to power most of California.
- CN Tower, at 1815 feet the world's tallest free-standing structure, looming over Toronto. Built as a broadcast communications facility, a Sikorsky helicopter hoisted the crowning antenna for which the tower was erected. A pair of 10-ton counterweights are attached to the mast to keep the tower from swaying too much. Designed with the aid of a wind tunnel, it can withstand 260 mph buffets.
- The Panama Canal. The severing of North and South America still ranks as one of man's greatest victories over geography. Today the canal operates much as it did in 1914. From the Caribbean Sea, a ship steams through a 7-mile dredged channel, then is towed into the 1,000-foot long Gatun Locks. Raised 85 feet, it then crosses Gatun Lake and the Gaillard Cut. The Pedro Miquel Locks drop the ship 31 feet; the Mira-flores Locks let it down another 54 feet.
Gravity, not machinery, feeds water into the locks. In each transit, 52 million gallons of fresh water is lost, though it is quickly replaced by Panama's heavy rainfall.
- The Golden Gate Bridge, the tallest suspension bridge erected to date, hanging from two 746-foot high towers. Its cables, each a yard thick, are the biggest ever to support a bridge. The bridge's grace belies its strength. It survived the 1989 earthquake, and weather has shut it to traffic only three times in 60 years.
- The Channel Tunnel, the newest of the seven wonders, which cost nearly twice as much as anticipated and ran more than a year behind schedule. The 31-mile link between France and England fulfilled a centuries-old dream and it rolls infrastructure and immense machinery into a transportation system of unprecedented ambition.
- The Netherlands North Sea Protection Works, which consists of two monumental steps the Dutch took to win their struggle to push back the sea. Step one is a 19-mile-long enclosure dam built between 1927 and 1932. The im-mense dike, 100 yards thick at the waterline, collars the neck of the estuary once known as the Zuiderzee.
Step two was the Delta Project to control the treacherous area where the mouths of the Meuse and Rhine rivers break into a delta. The crowning touch was the Eastern Schelde Barrier, a 2-mile barrier of steel gates slung between massive concrete piers. The gates fall only when storm-level waters threaten.
- The Empire State Building. Although no longer the world's tallest building, it remains the epitome of the skyscraper, the defining architecture of the century.