A massive bed of 400 stainless steel nails set in the rural New Mexico, Walter De Maria’s The Lightning Field forms a sparse grid in the empty desert. Arranged at the same height so they could suspend a single flat pane on top, the polished metal poles do attract lightning, but not as frequently as the name implies. Guests can book a cabin on the grounds for an overnight stay to stare at and contemplate the one mile-by-one kilometer artwork. Even without an electric flash, seeing the sunlight reflect off rows of steel is a mind-blowing sight in itself.

Built in 1970, Robert Smithson’s 1500-foot long curlicue of mud, salt crystals and rocks is considered an icon of land art and statement on the nature of entropy. The sculptor, who declared that museums were simply "mausoleums for art,” scouted out locations in Utah for this work, and settled on Rozel Point, in part due to its red hue and nearby industrial remnants. To construct the huge outcropping into the lake, he hired a local construction company to push 6,650 tons of material into the water. "That was the only thing I ever built that was to look at and had no purpose,” said the contractor in an interview. "It was made just to look nice.” The counter-clockwise spiral has turned from black to white-against-pink due to the gradual accumulation of salt. If you’re visiting, check ahead; the lake occasionally submerges the sculpture based on shifting water levels.

Famed light artist James Turrell has been working on transforming this extinct volcano north of Flagstaff, Arizona, into his own personal sky observatory for decades. Whereas many of his past and existing installations have caused epiphanies due to the magical way they frame the sky’s changing light, this 600-foot-tall cylinder of earth and stone may cross the line between artistic practice and religious architecture. For perspective, the finished first phase required the removal of 1.3 million cubic yards of earth. The sheer scale makes Turrell’s grandiose artistic statement— it “will bring the light of the heavens down to earth, linking visitors with the celestial movements of planets, stars and distant galaxies”—actually seem a little more grounded.

Under construction since 1971, Charlie Ross’s observatory will be an 11-story monument to astrology, and, whenever aliens decide to reveal themselves and appear above the Earth, a perfect place to park their spaceships. The temple-like structure has been designed to line up with Earth’s axis and align with planetary motion, in effect working as a sundial, compass and pointer aimed at the heavens.

Nancy Holt’s tubular installation will make sure you never look at pipes the same way again. Four 18-foot-long concrete cylinders, set up in an “X” pattern on an open expanse of northwestern Utah, provide another method of framing the landscape and stars, a "memory trace" that tries to communicate celestial movements via a more human-scale story. The tunnels are arrayed so that each open end catch the sun as it passes the horizon during the solstices, while holes drilled in the tunnels replicate the star patterns of different constellations.

Completed in the mid-‘80s by Michael Heizer, this series of earthen mounds 85 miles southwest of Chicago recalls the religious structures constructed by Native Americans in the Midwest and elsewhere. Five representational figures, such as this 685-foot-long water strider, fill in a crook of the Illinois River at Buffalo Rock State Park. Heizer’s work served both artistic and environmental purposes; formerly a strip mining site, the now-green mesa was once a destination for dirt bikers, who loved racing up and down the steep gorges.

In 1979, artist Robert Morris, convinced that an artist’s true calling was to reclaim what industry had ruined, turned a former gravel pit into a slow, sloping work of land art. The 3.7-acre site, formerly rural but now uncomfortably close to the suburbs, stands as a landmark in environmental reclamation. It’s one of the few works of art that was funded by the U.S. Department of Mines.

Swiss artist Ugo Rondinone’s excellent description of these day-glo rock piles—the seven "totems" consist of "locally sourced" boulders—offer a window into the artificiality he seeks to skewer with this temporary art installation in the Nevada desert. The idea is to present a contrast between the real and the artificial, between the majestic mountains and the electric excess of Las Vegas. Rondinone’s piece will be up until the middle of 2018; in the world of land art, a “temporary installation” tends to stick around for a bit.

The last work of Robert Smithson, this earthwork on Tevocas Lake, an artificial body of water, completes the trilogy he started with Spiral Jetty (the second project, the Broken Circle, is in Holland). The large earthen curve on remote ranchland in the Texas panhandle, a play on irrigation ditches, was commissioned by Stanley Marsh, an art patron who paid for other monumental works (including the more iconic Cadillac Ranch, a series of buried classic cars located nearby). Originally, when the water level hit its peak, the structure allowed one to walk about amid the temporary lake. Smithson died before seeing the structure completed: Richard Serra, Nancy Holt, and Tony Shafrazi finished the project after his death in 1973.