The American artist Michael Heizer has never really articulated his intention for City, a monumental, sprawling complex of mounds, geoglyphs and concrete pyramids set in the brutally hot and inaccessible high desert of Nevada, about three hours north-west of Las Vegas. But after a 50-year wait, this week visitors will finally have the opportunity to start forming their own interpretations of the work by the 77-year-old land artist. The sculpture is not ritualistic and may not be entirely understandable or necessarily useful. Its presence alone may be its greatest strength. “I can remember walking the land with Michael in 1973. [There was] nothing there but me, Michael, a few survey markers and a lot of wind,” says Barbara Heizer, the artist’s former wife, who spent 17 years in Nevada from 1974. She recalls that he had the project all planned out. “But maybe he didn’t think it would take this long. When you jump off a cliff like this, and you have no financial support, it’s not easy. But he always wanted to get this done.” City, which is 1.5 miles long and half a mile wide, joins a series of land art masterworks that includes Robert Smithson’s Spiral Jetty in Utah, Walter De Maria’s Lightning Field in New Mexico and James Turrell’s Roden Crater in Arizona – each created by a loose group of artists who set out in the late 1960s to free art from the confines of the gallery. For a previous large-scale project, Double Negative, from 1969, Heizer cut a 1,500ft-long, 50ft-deep, 30ft-wide trench on to facing slopes of the Mormon Mesa in Nevada, which required blasting and digging out 240,000 tonnes of rock. “There is nothing there,” the artist once said, “yet it is still a sculpture.” Since then, he has completed many projects, including Levitated Mass, a 2012 large-scale sculpture that caused crowds to line the bridges and service roads of an LA freeway as a 340-tonne boulder was moved from East Los Angeles to the Los Angeles County Museum, proving that moving giant stones is a contemporary as well as prehistoric preoccupation. Heizer’s father was an archaeological anthropologist. Born in Berkeley, California, the artist travelled to Peru and Mexico as a teenager, and later to Egypt. “I think a lot of things were brewing for him in terms of his work then,” says Barbara Heizer. “He always wanted to build City after Double Negative. That was the plan from day one. It’s one person’s focus and point of view.” City found a supporter in the late US senator Harry Reid, who was reportedly enthralled by the project and Heizer’s embrace of the landscape. Reid helped to stall proposals for a railway line to carry nuclear waste to a proposed storage facility under the nearby Yucca Mountain. The surrounding landscape was protected by the Obama administration, and City sits within the 704,000-acre Basin and Range National Monument, which also contains sacred and cultural Native American sites dating back 13,000 years. In protecting the land, President Barack Obama noted that Heizer’s project is “one of the most ambitious examples of the distinctively American land art movement”. Before City was completed, the art critic Dave Hickey wrote: “The roads and domes and pits within the excavation are elegantly curbed into long, quiet Sumerian curves. They restore our sense of distance and scale, so the complexity of City reveals itself as a gracious intervention in the desert … composed and complete.” It is not necessary to know Heizer’s intentions for the sculpture. Smithson, the unassigned philosopher of the land art group, expressed interest in redefining used mines and piles of slough, and activating the sculptural side of human activity. “It’s a big piece of nature, of the real world, in an art world that’s so much about fantasy, the mind, the irrational, dreams and concepts,” says the artist and critic Walter Robinson. “I often think when I see one of these art products, ‘wow, what a piece of work that is.’ It doesn’t matter if I like it or not, I’m overwhelmed by the intensity of the artist’s ambition.” For some of the land artists, the material was the land itself, hence the term “Earth Art”, and they proclaimed to remake art from scratch. In turn, they influenced a generation of artists, including – in Britain – Richard Long and Andy Goldsworthy, who followed in making sculpture that was part of the fabric of the land, but often made their own projects more mutable with the natural world. The land art movement came into being at a time when the ecology movement in the US was taking shape. By creating work that could not be exchanged and required engaging with elements of the environment, land artists called on the viewer to challenge their perceptions of art. Visitors to the City sculpture will be limited to six a day, and Heizer has expressed concern that too many could damage the work. But the completion of City hasn’t pleased everyone. Char Miller, professor of environmental analysis and history at Pomona College, California, acknowledges Heizer’s dedication but questions “the land artists’ drive to tear apart the land because they thought they could do it better. That rubs up against an environmental culture that argues that the integrity of places is the integrity of places and beautiful unto itself.” However, such arguments may detract only slightly, if at all, from Heizer’s achievement. Robinson considers City “mythical and atavistic”. “It’s Sisyphus pushing the rock up the hill only for it to roll down again,” he says. “It has to be one of the grandest, most ambitious efforts that an individual artist has ever undertaken.”