How were they built? From Giza to Easter Island, 6 ancient mysteries that remain unexplained

Despite technological advances and decades of research, there are several historical artifacts that continue to challenge modern understanding. Each of them hold clues, but no theory fully explains how or why they were made. Here is a list of 6 such artefacts.

The Great Pyramid of Giza, believed to be constructed around 2580–2560 BC, comprises roughly 2.3 million stone blocks, some of which weigh up to 15 tonnes. It is assumed to be built without cranes, wheels, or iron tools and continues to baffle experts. Recent research around the construction suggests that the workers used wooden sledges and poured water on sand to reduce friction while moving the stones. Several archaeological evidence prove that the labour force consisted of skilled workers, not slaves, receiving food and healthcare. In 1990, worker tombs were found near the pyramids which indicates that they were respected members of society, possibly tax-paying families.

In Peru’s southern desert, the Nazca Lines stretch across over 1,000 square kilometres. These lines were created between 500 BC and 500 AD. However these are not simple lines, but massive geoglyphs that depict animals, plants, and shapes which are only visible from above. The existing theories about their purpose vary, while some theories suggest astronomical calendars, others propose religious or water-related functions of these lines. Despite the satellite imagery and modern mapping, the exact reason behind their construction still remains uncertain.

This Antikythera Mechanism was recovered in 1901 from a shipwreck off the Greek island of Antikythera, and is believed to date back to around 150 BC. This mechanism features over 30 bronze gears and is assumed to have predicted solar and lunar eclipses, olympic games dates, and planetary movements, during the time, since the exact usage of the mechanism remains a mystery. Its precision pre-dates similar mechanical devices by over a thousand years. X-ray imaging still continues to reveal new components, but who built it and how it was used remain unclear.

Discovered in 1912, the Voynich Manuscript is a 240-page book filled with unknown writing and strange botanical drawings which could not be decoded till date. After Radiocarbon dating, it was revealed that the manuscript was written during the early 15th century. Despite decades of study and advanced AI analysis, the language remains undeciphered. Its drawings of unidentified plants and even astronomical charts adds to the mystery. Whether it’s a hoax or lost knowledge is still debated by many.

Between the 9th and 11th centuries, swords inscribed with “+VLFBERHT+” appeared across Europe. What's interesting is that these are not ordinary swords, but are made with high-carbon steel, purer and stronger than other blades of the time. The forging technique in the swords resembles crucible steel, which is believed to have arrived from the Middle East. Over 170 such swords have been found till date, but their precise origin and production methods remain unknown.

The Moai of the Easter Island continue to fascinate both archaeologists and history enthusiasts alike. These statues were carved by the Rapa Nui people between 1100 and 1500 AD, weigh up to 80 tons and were transported over miles of rugged terrain. Theories on their movement range from wooden sledges to a 'walking' technique of using ropes to pull the statues. Their purpose, whether religious, social, or symbolic, still remains debated. Nearly 1,000 statues have been documented, and the longest journey to transport them from is estimated at 11 miles.