If you've ever wondered how they built Stonehenge, how they shifted Easter Island's Moai statues into place or how many workers it took to construct the pyramids, then this list of the most awe-inspiring ancient feats of engineering is for you. The following entries are all marvels of extraordinary technical prowess and innovation, and required a staggering amount of manual labour.

From youngest to oldest, read on for the most remarkable feats of engineering ever achieved in the ancient world...

The Moai statues of Easter Island are among the most baffling ancient monuments of all. It took a year to create each of these 800+ monolithic statues using basic stone picks called 'toki'. The statues were then placed atop chieftains' tombs. Moving them into position was another impressive feat, as they each weigh up to 80 tonnes. Many believe they were rolled on logs, some think they were transported upright, and a few even think they were rocked from side to side to imitate walking.

This archaeological site was once the location of a sacred Incan building constructed with giant boulders weighing up to 125 tonnes apiece. The tower walls are made up of dry stones in a zigzag formation (check out the enormous size of the lower wall stones), which are so well aligned that not even a sheet of paper can be inserted between them. Historians are still baffled by how the stones were transported nearly two miles (3km) from the quarry to the site. Just how did they do it?

The Incan Empire constructed this beautifully planned royal estate amid landslide-prone slopes and heavy rain. Their genius revolved around water: once they’d built a stone canal and implemented an efficient water drainage system, the 170-odd structures were much easier to build. Without mortar they used ashlar to fit carved granite stones together, and with no steel or iron tools they used bronze and stone. It’s believed that they used levers and ramps to transport the 15-tonne stones. It’s estimated that up to 60% of construction is now underground.

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Built during the Pueblo III period (AD 1150-1300), Mesa Verde consists of 600 ancient clifftop dwellings. Carved into sandstone alcoves, most sit on firm bedrock, and residents likely moved here for greater protection against the elements. These smaller residences consisted of just a few rooms, but by far the most famous is the Cliff Palace (pictured) which contained more than 150 rooms and 23 kivas (large circular underground rooms used for rituals). It must have been arduous to build, and nobody knows why the village was eventually abandoned...

The rock-hewn churches of Lalibela consist of 11 medieval buildings carved out of rock. These vast monoliths feature chiselled doors, windows and columns, along with an extensive system of drainage ditches, ceremonial passages and catacombs. Plunging some 131 to 164 feet (40 to 50m) into the ground, inside are mural paintings and former royal residences. These staggering feats of engineering are widely believed to date to King Lalibela’s reign (AD 1181-1221).

The elaborate Tikal complex stands out among Guatemala's dense green jungle. Among the ancient Mayan temples, shrines and acropolises is the Temple of the Two-Headed Snake, one of the tallest pre-Columbian structures in the Americas. The structures were mostly built using plaster-surfaced stones raised on great platforms. They featured wide staircases and were decorated with detailed stucco facades. Their architectural patterns are believed to have astronomical associations, although there’s still much more to find and understand.

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Hidden under layers of volcanic ash and jungle vegetation until 1835, Borobudur is the largest Buddhist temple in the world. Yet we still don’t know much about its construction or original purpose, with historians left to comb through the thousands of carved reliefs for clues. It’s believed to have taken 75 years to build using andesite (grey volcanic rocks), which was taken from adjacent quarries, cut, transported and laid without mortar. 

You’ll find the aptly named Leshan Giant Buddha carved into red sandstone cliffs in southwest China. It took the Tang Dynasty 90 years to build the monument, the tallest Buddha sculpture in the world. Behind Buddha’s 23-foot (7m) ears is a functioning drainage system which has stopped erosion of the 233-foot-tall (71m) sculpture. Thanks to the softer sandstone material, craftsmen were able to show off their skills in creating symmetrical features – 1,021 buns in his coiled hair and feet so large that up to a hundred people can squeeze onto them. 

This sacred site is home to Hindu, Buddhist and Jain temples carved from volcanic basalt stone. Among the decorated caves is the grand Kailasa Temple which, at 104 feet (32m) high, is the largest rock-cut monument in the world. It was formed from the sloping basalt hill and features a three-storey town with an octagonal dome. Then there’s the architectural detail to admire: bases, beams, brackets, pilasters and carved reliefs. See this slice of ancient India for yourself near the modern city of Aurangabad.

You might not think the desert would house the oldest skyscrapers in the world but the 1,700-year-old town of Shibam proves otherwise. Nicknamed the Manhattan of the desert, some 500 mud-brick towers were built to protect the area from flooding and be a vantage point for spotting incoming attackers. While many have been rebuilt, Shibam nevertheless showcases the earliest examples of multi-storey vertical structures in the world. Buildings span between five and 11 storeys, with some reaching heights of 100 feet (30m).

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Northeast of Mexico City lies Teotihuacan, where you’ll find some of the largest pyramid-like structures outside Egypt. They once formed a 22 mile-wide (35km) metropolis in a grid-like structure that aligned with key geographic, geodetic and celestial points. It’s pretty impressive stuff when you consider that the Pyramids of the Sun and Moon were built between AD 1 and 250.

At 80 feet (24m) wide and 127 feet (38m) tall, the Al-Khazneh (or Treasury) was constructed using simple iron tools and hammers. This two-storey sandstone sculpture was carved out of the pink sandstone cliffs and includes massive columns and mythological creatures, inspired by ancient Greece and Rome. You might not expect to see such a staggering structure in the desert but Petra formed part of an ancient trade route between Arabia, Egypt and the Mediterranean Sea.

When you think of impressive ancient buildings, Rome’s Colosseum likely comes to mind. Measuring 617 feet (188m) in length, 511 feet (156m) in width and 187 feet (57m) in height, around 80,000 spectators once flocked to watch gladiator fights, executions and battle re-enactments. The oval-shaped building was constructed from stone, cement and bricks and bound with iron clamps. There’s still great debate about whether the Colosseum was filled with water for naval battle recreations.

Sigiriya, or Lion Rock, is an ancient fortress carved into a 656-foot (200m) vertical rock face near Dambulla. During its long history it served as a royal palace and monastery and is made up of a citadel, upper palace, gardens and lion-shaped gateway. There was remarkable ancient engineering at play here, with canals, lakes and water pumps giving the fortress a crucial lifeline while demonstrating skilled urban planning and advanced technology.

The Aqueduct of Segovia supplied water from the Frio River to the city up until the 20th century. The remaining portion stands at 94 feet (26m), and the pillars and arches of this two-storey arcade were made of solid stone and needed little restoration work until the 15th and 16th centuries. Stretching 8.6 miles (14km) across the rolling landscape, the lower arches alternate in height and remain a powerful demonstration of the engineering prowess of the Roman Empire.

One of the most famous walls of all time, the Great Wall of China stretches 13,000 miles (21,196km) across the country’s northern border, from Shanhaiguan in the east to the Gobi Desert in the west. Thousands upon thousands of workers are thought to have constructed the wall, built to protect Chinese land and culture. It was first completed around 221 BC but it’s been repaired and rebuilt over the years. The Ming Dynasty (1368-1644) added garrisons and watchtowers.

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One of the most exciting archaeological discoveries in history, Xi’an’s Terracotta Army is nothing short of awe-inspiring. And huge: around 8,000 pottery soldiers and archers, 130 chariots and 520 horses were unearthed in three pits in an area spanning 215,278 square feet (20,000sqm). It’s believed this army guards the body of Emperor Qin Shi Huang, who died in 210 BC and whose tomb lies around a mile away. It took some 700,000 workers 40 years to build this impressive site by hand with basic tools.

Located inside the Mirador-Rio Azul National Park, this pre-classic Mayan city was completed at some point between 600 BC and AD 100. Its largest pyramid is La Danta – at 230 feet (70m) tall, it hasn’t been swallowed up by the jungle like other structures. It’s estimated that some 15 million days of labour were used to create this still-standing pyramid.

How beautiful is the Sanchi Stupa? One of the oldest stone structures in India, it was first built around 300 BC to house relics of the Buddha, and stood at 54 feet (16m) high. Around 185 BC, the Stupa was reconstructed at double its original size. Stone slabs were re-used to create a flattened dome, atop which stand three structures symbolising Dharma (the Wheel of Law). It currently stands at 71 feet (22m) high and among the carved gateways and staircases you’ll spot intricate carvings and reliefs.

The Parthenon is undoubtedly one of the most recognisable temples in the world. Just under 45 feet (13m) tall, it was built in honour of the Greek goddess Athena by thousands of ancient Athenians who extracted and transported huge quantities of marble. They used enormous pulley systems and wooden cranes which were innovative at the time. They were apparently able to lift a 10-tonne marble slab to a height of 49 feet (15m) in just 20 minutes.

The colossal Gate of All Nations was constructed in Persepolis (in modern-day Iran) during the reign of Xerxes I and was a meeting place for the kings, nobles and other elites of the Achaemenid (Persian) Empire. The structure was once part of a huge building with doors in the east and west, and a cavernous hall between them. Here you can see the gate flanked by four-legged statues said to ward off evil spirits, backed by 52-foot-high (16.5m) Ionic columns that once held up a mighty roof.

Van Fortress sits on a steep precipice overlooking Tushpa, near modern-day Van in Turkey. Rubble stone, mud brick and cut stone material were all used to construct this hilltop complex, and its eight rock-cut tombs with 29-foot-tall (9m) chambers are nothing short of amazing. It would have required precise mathematical and architectural knowledge to construct the complex, and its endurance demonstrates that Urartian architects were some of the most skilful in the Near East.

Chand Baori is awe-inspiring both in its appearance and its construction. Built in the 10th century BC to supply water to the Abhaneri village in eastern Rajasthan, its 3,500 steps descend some 64 feet (19.5m) into the earth, forming one of the largest and deepest step wells in the world. Its symmetrical geometry is incredible – especially when you consider that it was built with simple tools. The ancient site also features an enclosed rectangular courtyard with windows, a three-storied pavilion, pillar-supported galleries and sculpture-clad balconies. 

This mighty circle of stones rising from Salisbury Plain still baffles experts. Erected in the late Neolithic period, the mystery of how (and why) the enormous sarsen stones and smaller bluestones were transported all the way from Pembrokeshire has fascinated people for centuries. Evidence suggests that part of the famous stone circle was first built near the Pembrokeshire coast before being dismantled and rebuilt in Wiltshire. Somehow, this masterpiece of engineering was created using only simple tools and technologies. 

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It’s still something of a mystery how the ancient Egyptians constructed the pyramids of Giza, although there are a couple of theories leading the way. The ramp theory suggests they shifted stones with ropes, sleds and wet sand (to reduce friction) up spiralling ramps, while the water shaft theory describes how specially-created canals helped transport the materials. However it was achieved, immense strength (and manpower) was required to construct each pyramid. Their legacy is reflected by their status as one of the Seven Wonders of the Ancient World.

Ancient Mesopotamia (8000 BC-2000 BC) left some of the most remarkable engineering of its era, and this is showcased in modern-day Pakistan’s Great Bath. This rectangular bath was likely used for special occasions and ceremonies, with two wide staircases leading down to it. Measuring 38 feet (12m) long, 22 feet (7m) wide and up to eight feet (2.5m) deep, baked bricks were used in its construction with a natural tar material to keep it watertight. An adjacent well provided water and there was also an established drainage outlet, along with adjoining rooms likely used for changing. 

Only discovered in 1994, Gobekli Tepe is considered the world’s oldest religious complex. Excavations revealed vast limestone pillars set in circles, six temples and megaliths carved with lions, scorpions and snakes. How these 50-tonne T-shaped pillars were shifted into position by hunter-gatherers remains a mystery. If that's not enough, archaeologists believe there are still more temples to unearth.

Now discover what the Seven Wonders of the Ancient World would look like today