Flevopolder is a 374.5-square-mile artificial island in the Netherlands, which is far and away the largest artificial island in the world. The island was created as part of several land reclamation projects, with eastern Felvopolder opening in 1957 and the southern portion in 1968. In 1986, the artificial island officially became the 12th province of the Netherlands.

The Jing-Hang Grand Canal, commonly known as the Grand Canal, is the longest artificial waterway in the world. A UNESCO World Heritage Site, the canal begins in Beijing and connects to the city of Hangzhou, linking the Yellow and Yangtze Rivers. The canal’s total length is around 1,100 miles long, and it reaches a maximum height of 137 feet.

Cascata delle Marmore in central Italy stands 541 feet tall, making it the world’s tallest artificial waterfall. The Romans constructed the waterway in 271 BCE, redirecting water from the Velino River into the Nera River. Several new channels were added to the falls in the 15th and 16th centuries

The Lion’s Mound is an artificial hill in Belgium that commemorates the battle of Waterloo, specifically the place where the Prince of Orange was injured on June 18, 1815. The mound was created between 1823 and 1826 and is topped with a cast iron lion sculpture. The hill is around 130 feet tall and features 226 steps ascending along its slope.

Mostly contained underground, the Great Man-Made River is an expansive network of pipes supplying fresh water throughout Libya. It is considered the largest irrigation project in the world. After water was discovered underground in Libya’s southeastern desert region in the 1950s, construction on the “river” began and was completed in 1991.

René-Levasseur Island is an artificial landmass in Lake Manicouagan in Quebec that was formed in 1970 when the surrounding reservoirs were flooded, merging two crescent-shaped lakes around the island. The picturesque island spans around 780 square miles.

Rediscovered by accident in 1992, the Longyou Caves are a series of 24 artificial sandstone caves in the Zhejiang province of China. Historians believe that the caves were constructed by ancient peoples over 2,000 years ago. The original purpose of the caves remains unclear, but theories range from their use as quarries to mausoleums, storage, or dwellings.

The leafy vegetation of the Nebraska National Forest stands out among the rest of the Great Plains, as these 141,864 acres are entirely human-made. The area was completely barren of trees before botanist Charles E. Bessey began in 1902 to attempt to restore a forest which formerly stood on the land. The result was the largest artificial forest in the United States.

Not only is Nieuw Land the Netherlands’ newest national park, established in 2018, but it was also created entirely by humans. Nieuw Land was formed as part of the world’s biggest land reclamation project, which saw the parklands emerge from what used to be the South Sea. The park is particularly idyllic for birdwatchers and is known for its white-tailed eagle sightings.

Lake Volta spans 3,283 square miles, accounting for 3.6% of Ghana’s total land area, and is the world’s largest artificial reservoir by surface area. By volume, however, Volta comes in third after Lake Kariba (located along the border of Zambia and Zimbabwe) and the Bratsk reservoir in Russia. The Akosombo Dam that forms Lake Volta provides electricity to Ghana plus nearby countries such as Benin and Togo.

The Palm Jumeirah Islands are a series of artificial islands off the coast of Dubai in the United Arab Emirates. The islands were created using approximately 7 million tons of rock and over 4 billion cubic feet of sand, which was formed into the shape of a palm tree. Two more palm islands were initially planned, but thus far only the Palm Jumeirah has been completed.

The Big Hole of Kimberley, South Africa, began to form during diamond mining operations in 1871. From that year until 1914, around 50,000 miners dug the ever-expanding hole, which was excavated to a depth of nearly 800 feet. The hole now descends from the surrounding plains to a stunning pool of turquoise water below.

The “Door to Hell” is the nickname for the Darvaza Crater, which formed in the early 1970s when the ground beneath a Soviet drilling operation in Turkmenistan gave way. The brilliant glowing embers of the 225-foot-wide and 99-foot-deep crater have burned ever since, standing out among the otherwise barren landscape of the Turkmeni desert.

Nicknamed the “Little Grand Canyon,” Providence Canyon descends as deep as 150 feet in southwest Georgia. Rather than Mother Nature, the picturesque gullies of the state park were created due to poor farming practices in the 1800s. The canyon is home to many natural wonders, though, such as the rare Plumleaf Azalea which blooms annually between July and August.

Opened in 1914, the Panama Canal was an engineering marvel that linked the Atlantic and Pacific Oceans through the Isthmus of Panama. Approximately 240 million cubic yards of earth were moved to complete the 40-mile-long canal, which the U.S. oversaw from its opening until ceding it back to Panama on December 31, 1999.

Throughout Asia, rice farmers have carefully cultivated terraced, mountainside fields to grow the beloved grain. Some of the more visually striking rice paddies include the illuminated terraces of the Ishikawa Prefecture, Japan, and the centuries-old paddies of Vietnam’s Yen Bai Province, the latter of which is home to Hmong farmers who have been cultivating the grain for centuries.

Fly Geyser is one of three human-made geysers on the edge of the Black Rock Desert in Gerlach, Nevada. The geyser has a unique rainbow color thanks to the mineral deposits covering its multiple cone-shaped openings, which shoot water up to five feet in the air. It first erupted in 1964, after drilling from a geothermal energy company penetrated geothermal pools.

Located on the Mendocino Coast of Northern California, Glass Beach was originally a trash dumping site between 1906 and 1967. Included among the garbage were glass bottles and car headlights that, over time, transformed into tiny crystalline glass pebbles that now pepper the beach. The pebbles come in a kaleidoscope of colors that correspond to the type of trash they originated from.

Despite shrinking water levels in recent years due to an ongoing drought, Nevada’s Lake Mead — which was formed by the adjacent Hoover Dam in the 1930s — is America’s largest artificial body of water. At its maximum capacity, the lake holds 9.3 trillion gallons of water and reaches an elevation of 1,220 feet, though it hasn't approached that full capacity since 1999.

Located at the northern end of Central Park in New York City, the Jacqueline Kennedy Onassis Reservoir honors the former First Lady who was known to frequently jog around the park’s perimeter. The artificial body of water, which spans 106 acres, was constructed between 1858 and 1862, becoming the largest human-made body of water in the world at the time.