- Pyramids at Giza, Egypt
- Suez Canal, Egypt
- Tarbela Dam, Pakistan
- Durrat Al Bahrain, Bahrain
- Bingham Canyon Mine, Utah
- Almeria greenhouses, Spain
- Dubai waterfront, United Arab Emirates
- Nile delta aquaculture, Egypt
- Akashi Kaikyo Bridge, Japan
- Aswan High Dam, Egypt
- Pontchartrain Causeway, Louisiana
- Pyramids at Giza, Egypt
- Three Gorges Dam, China
- Boeing Plant, Everett, Washington
- Carajas Mine, Brazil
- Central Park, New York
- Nagarunja Sagar Dam, India
- Panama Canal, Panama
- Angkor, Cambodia
- All-American Canal, California
- Great Wall of China
- Colorado ski resorts
- Jabal Tuwayq agriculture complex, Saudi Arabia
- Desert Sunlight solar project, California
- Makgadikgadi Salt Pans, Botswana
Pyramids at Giza, Egypt
Provided they get close enough, it probably wouldn’t take alien visitors long to detect the presence of humans on Earth. Many modern man-made structures—dams, canals, bridges, mines, highways, greenhouses and so on—are visible to the naked eye from space.
Several ancient sites, from walls and pyramids to mysterious landscaping, can also be seen from high above. Which of these works might impress aliens the most? Check out these contenders…
Suez Canal, Egypt
The continent-dividing extent of this waterway of 193 kilometres (120 miles) connecting the Mediterranean and Red seas can be seen in this photo taken from the Space Shuttle Columbia.
Tarbela Dam, Pakistan
This rock-filled enormity on the Indus River looks impressive enough from the International Space Station. But as with other dams on this list, the most spectacular aspect of Tarbela’s 106-million-cubic-metre (139-million-cubic-yard) volume is the massive man-made reservoir it created.
Durrat Al Bahrain, Bahrain
Were they aboard the International Space Station, residents of this man-made island resort wouldn’t be able to see their individual abodes. But their stunning 1,032-villa neighbourhood off the southeast shoreline of Bahrain is clearly visible.
Bingham Canyon Mine, Utah
Photographed from the International Space Station, the open-pit Bingham Canyon Mine lives up to its status as one of the largest man-made excavations in the world. It extracts porphyry copper from the mountains southwest of Salt Lake City.
Almeria greenhouses, Spain
Photographed from the International Space Station, tens of thousands of tightly packed plastic greenhouses make a huge swath of southern Spain look like a year-round ice-cap.
Dubai waterfront, United Arab Emirates
More than 50 million cubic metres (65 million cubic yards) of sand was dredged to construct these gigantic man-made archipelagos dotting the Persian Gulf. Here, the Dubai waterfront looks truly spectacular from the International Space Station.
Nile delta aquaculture, Egypt
The incredible extent of fish farming along the northeast coast of the River Nile’s delta is revealed by this photo taken from the International Space Station.
Akashi Kaikyo Bridge, Japan
The record-setting 1,991-metre (6,530-foot) length of the Akashi Kaikyo Bridge, which links the city of Kobe to Awaji Island, is highlighted by this photo taken from NASA’s Terra spacecraft.
Aswan High Dam, Egypt
This photograph taken from the International Space Station reveals the stunning 3,830-metre (12,565-foot) length and 1,000-metre (3,281-foot) width of one of the world’s largest earthen embankment dams. What it doesn’t show, however, is the structure’s 111-metre (364-foot) height.
Pontchartrain Causeway, Louisiana
One of the longest water-crossing bridges in the world, the 39-kilometre (24-mile) causeway across Lake Pontchartrain resembles a sinewy thread in this photo taken from the Landsat 7 satellite.
Pyramids at Giza, Egypt
The near-perfect symmetry and shape of these 4,500-year-old marvels—not to mention their gigantic size—is revealed by this image taken from the International Space Station.
Three Gorges Dam, China
Look upstream from this record-setting dam—in this case, with help from NASA’s Terra spacecraft—and the original width of the Yangtze River provides a prime example of how human beings have changed the surface of the Earth.
Boeing Plant, Everett, Washington
The largest building in this photo taken by NASA’s Terra spacecraft is used by Boeing to construct several 747 aircraft at the same time. Covering 39 hectares (98 acres), it’s the largest building in the world.
Carajas Mine, Brazil
The world’s largest open-pit iron ore mine, here photographed by NASA’s Terra spacecraft, is estimated to contain more than seven billion tons of iron ore, as well as gold, manganese, bauxite, copper and nickel.
Central Park, New York
The 340-hectare (840-acre) green rectangle is Manhattan’s most recognizable feature in this photo taken from the International Space Station.
Nagarunja Sagar Dam, India
The largest masonry dam on Earth holds back a truly mind-boggling amount of water, as this photo taken from NASA’s Terra spacecraft clearly shows.
Panama Canal, Panama
The 65-kilometre-long (40-mile-long) waterway linking the Atlantic and Pacific oceans looks like a kind of collar in this photo taken during a space shuttle mission.
Cleared of the dense jungle that shrouded it for centuries, this enormous ancient temple complex is now visible from space, as this radar image taken during a space shuttle mission reveals.
All-American Canal, California
At 130 kilometres (80 miles) in length, this border-skirting aqueduct is the world’s largest irrigation canal. This image, taken from aboard the International Space Station, shows about 12 per cent of the AAC.
Great Wall of China
Commonly cited as being visible from space, these fortifications that run 8,850 kilometres (5,500 miles) are in fact difficult to spot from orbit. Photographed from Space Shuttle Challenger, the wall looks more like a river as it crosses Quinhuangdao, China.
Colorado ski resorts
The Breckenridge and Copper Mountain ski resorts show off their scores of man-made trails in this image taken from the International Space Station.
Jabal Tuwayq agriculture complex, Saudi Arabia
Resembling hundreds of dark dots from the Space Shuttle Columbia, these swing-arm irrigated farms draw on subterranean water reserves to grow crops in the Arabian Desert.
Desert Sunlight solar project, California
This 550-megawatt solar farm in the Mojave Desert generates enough electricity to power 160,000 homes. Covering an area of 16 square kilometres (six square miles) and comprised of 8.8 million cadmium telluride photovoltaic modules, the incredible scale of the project is revealed by this photo from NASA’s Terra spacecraft.
Makgadikgadi Salt Pans, Botswana
Photographed from the International Space Station, this huge soda ash- and salt-gathering facility is just one small section of central Botswana’s great salt flats.