It is one of the most spectacular natural wonders of the world, its vastness rarely failing to induce awe in those who see it. Now, visitors to the Grand Canyon are set to get even more stunning views – from a glass platform that enables people to gaze down directly at the chasm beneath.

The Skywalk, to be opened later today, features a horse-shoe shaped observation deck jutting out 70ft over the western lip of the canyon, from which tourists will be able to peer down at the full 4,000-ft drop to the bottom – affording a vantage point more than twice as high as the world’s tallest buildings.

Dubbed one of the greatest engineering marvels of the times, the platform, which has divided opinion, weighs around 500 tonnes but has no visible supports from above or below. Constructed using 4-inch-thick glass, it is held by giant steel bolts that have been driven 46ft into surrounding bedrock.

Giant shock absorbers will also prevent the structure, located over the vast chasm in the Hualapai Indian Reservation, from quivering under the weight of visitors.

The project, which took two years to complete, is the latest example of the changing fortunes of Native American tribes, many of which have been increasingly turning to tourism to generate income.

The Hualapai tribe, who own the site - located 120 miles east of Las Vegas - gave permission for a Las Vegas developer to build the $30m walkway to attract visitors to their remote section of the Grand Canyon, which lies several miles away from the more successful Grand Canyon National Park and has previously struggled to lure tourists to its Old West-style villages and tours.

But while some have hailed the initiative as a triumph for architecture, some Hualapai Indians have slammed it as a horrific blight on what they insist is sacred land, while environmentalists say it is another example of the canyon’s descent into tourist parody.

“We have disturbed the ground,” said 70-year-old Dolores Honga.“Our people died right there. It’s spiritual ground."

Kieran Suckling, of the Centre for Bio Diversity, said that the walkway signalled the imposition of a man-made marvel on the site of one of the natural wonders of the world. “The Eiffel Tower is an architectural wonder,” he told CNN. “But do I want the Eiffel Tower on the edge of the Grand Canyon? No.”

But Hualapai leaders defended the decision, insisting that they had weighed such concerns for years but with a third of the tribe's 2,200 members living in poverty decided they needed the tourist dollars.

Sheri Yellowhawk, a Hualapai tribal councilwoman who has been closely involved with the development of the project, said: “Our people have suffered poverty and unemployment for years. I don’t think we can be criticised for wanting to change that.”

Buzz Aldrin, the second man to step foot on the Moon after Neil Armstrong, and various Hualapai tribal leaders will be among the first to venture out onto the walkway at an opening ceremony later today. Those nervous about braving their way on the Skywalk may be somewhat reassured by architects’ promise that the structure is capable of supporting several hundred people simultaneously and will not be affected by powerful winds that often roar through the Grand Canyon.

Tickets for the walkway, which opens to the public on March 28, will cost around $25.

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