They've made a molehole out of a mountain - an amphitheater bigger than Paul Bunyan would ever need, streaked in shades of yellow and gray, that has widened and deepened over the course of a century.

The world knows it as the Bingham Canyon Mine."In 1967, when I started, you could tell when people began working here by whether they called it `The Hill' or `The Pit,' " says Louis J. Cononelos - whose father and grandfather worked there before him. For where once stood a mountain, rising above two forks in the narrow canyon southwest of Salt Lake City, the great bowl dips today.

It is:

- The largest man-made excavation on the planet, 21/2 miles across - a half-mile deep. That's about the equivalent of stacking the Empire State Building and the Sears Tower on top of each other - or, if you prefer, six LDS Church Office Buildings.

- One of the few man-made creations distinctly visible from space. The Great Wall of China is another commonly mentioned.

- "The Richest Hole on Earth," source each year for 320,000 tons of copper, 500,000 ounces of gold, 4 million ounces of silver and 20 million pounds of molybdenum.

- A major tourist attraction, usually listed up there with natural wonders like Utah's Zion, Bryce and Arches national parks.

In fact, the Roadside America Web site suggests, with perhaps a tongue-in-cheek sense of wonder, "Why bother with way-the-hell-out-of-the-way Grand Canyon when you can gaze at something just as spectacular only a half-hour drive from Salt Lake City?"

Cononelos is Kennecott Utah Copper Corp.'s director of government and public affairs. Among his responsibilities is overseeing the Bingham Canyon Museum, perched to good effect on the lip of the pit at an elevation of 6,800 feet above sea level. He, his staff and volunteers have made it an enlightening place - and just counted their millionth visitor.

The center, built in 1992, was moved to its present location and expanded two years ago. The access road shifted, too; the Bingham Highway through Copperton is no longer the way to get there. Visitors must turn through a gate a bit farther south, near the former site of Lark, pay a small fee and drive up a highway that cuts across the great tailings scree visible from throughout the valley.

The museum, open from the first of April through the end of October (weather permitting on both ends of the calendar), has seen as many as 3,000 people on a busy weekend or holiday; 5,000 dropped by during one company open house in 1996, Cononelos said. Half of the tourists are from out of state. About 170,000 visited in 1997, though the annual number has occasionally reached 200,000.

Cononelos believes freeway and highway reconstruction is having an effect. "I think people are finding it difficult to make their way through the maze," he said.

An overlook affords visitors a view of the pit's concentric rings and benches, the giant shovels (they chaw 98 tons in each scoop), the gigantic trucks, and, far below, the ore crusher that crunches rock into transportable portions. The plaza is also decorated with historic plaques, antique mining equipment, bits of buildings long gone and, of course, a Bunyanesque $20,000 Goodyear steel-belted radial from one of the 255-ton ore-hauling trucks.

The huge tire is a perennial favorite. "Everyone seems to want to get their picture taken by the tire," Cononelos said.

Inside are displays designed for just about every interest: for art enthusiasts (notably brass and bronze sculptures by Gary Prazen), historians, geologists, miners, tourists and schoolchildren.

"It's really well put together," said Dora Hunter. A fourth-grade teacher, she was directing 77 fourth-graders from Orem's Geneva Elementary School into the 90-seat auditorium to watch the museum's 15-minute video on a recent visit. Guided by a checklist, the students had been eyeing the models, maps and artifacts. Several seemed particularly taken with the Tonka-sized miniatures representing the trucks, shovels, cranes and other equipment used over the decades at Bingham Canyon.

This was the first time the Orem school had put the museum on its field-trip itinerary, and Hunter praised the volunteers for their help. Overall, it made for a nice trip - in part "because we can afford it." Museum tours are free to schoolkids.

The displays recall 150 years of history in the Oquirrh Range.

In 1848, pioneer brothers Thomas and Sanford Bingham built a cabin at the mouth of the canyon that came to bear their surname, intending to graze animals in the area. They noticed mineral-bearing rock, a centennial plaque notes, and that led to a bit of prospecting. However, Brigham Young suggested that "production of food for the settlers and thousands who were coming was more urgent than mining," so the Binghams abandoned prospecting and subsequently moved to Weber County, intending to someday take up where they left off. They never returned.

Soldiers under Col. Patrick Connor, based at Fort Douglas, did more serious prospecting in 1863. About a decade later, a boom in gold and silver mining was under way. Copper speckling the rock was deemed of too low a grade to be profitably mined - until young Daniel Jackling came along.

A metallurgical engineer, Jackling theorized that with intensive modern techniques, money could be made surface mining such copper. A hundred years ago, in 1898-99, a marker recalls, he conducted his first mill tests on ore taken from claims on a mountain rising above two narrow canyons in the Oquirrhs. In 1903, he and his partners formed Utah Copper Corp. By 1910, it was the biggest mining operation in the world - thanks to Jackling's vision and the dawn of the age of electricity, an industry that made use of copper's conductivity.

Gradually, The Hill, honeycombed with older mines, was eaten away. Also consumed by The Pit were small canyon towns and settlements, many of them with names reflecting the homelands of their inhabitants: Greek Camp, Frog Town and Japanese Camp - 40 ethnic groups in all, Cononelos said - as well as Winamuck, Highland Boy, Copperfield and, eventually, Bingham City.

"This was a little city-state," he said. Some 20,000 people - miners, shopkeepers and their families - "were living in this mining district in the 1910s and 1920s."

The exhibit hall is filled with memories from times - and places - past: photographs, histories, even the contents of a World War II time capsule from Copperton's old Bingham High School, including letters, helmets and grenades.

"We try to keep some of the things old-timers remember," Cononelos said.

Today, the Bingham Mine is open "24 hours a day, seven days a week, 365 days a year," Cononelos said, extracting 450,000 tons of material a day. The ore's grade is six-tenths of 1 percent copper - each ton of ore mined yields but 12 pounds of the metal, as well as traces of other metals.

A set of model-maps gives visitors a bird's-eye view of the evolution of The Hill into The Pit circa 1900, 1993, 1960 and 1990. The last one envisions the year 2020.

"When my grandfather started here, the life of the mine was expected to be 20 years," Cononelos said. That was the economic reality then. As it turned out, the predicted span was the same when his father began working at the mine, and when he did, too, years later.

Now The Pit is expected to last . . . yes, 20 to 25 years. And then underground mining may return, Cononelos said, because the valuable mineralized core that has already yielded great wealth dives deep, deep into the earth.

Kennecott Utah Copper's Bingham Canyon Mine visitors center, 25 miles southwest of downtown Salt Lake City, is open April through October, weather permitting, 8 a.m. to 8 p.m. seven days a week. Admission fees, which are donated to local charities, are $2 for motorcycles, $3 for passenger cars, $15 for mini tour buses and $30 for regular tour buses. There is no charge for school buses, Scout groups in uniforms or vans from senior citizen centers. For more information, call 252-3234.