The construction of Stonehenge in England, believed to be erected around 2500 BC, still baffles historians and archaeologists.
The identity and civilization of the Sea People, a group of seafarers who attacked Mediterranean cities around 1200 BC, remains a mystery.
The reason for the sudden abandonment of the Indus Valley Civilization around 1800 BC is still unknown.
The origin and purpose of the Nazca Lines, a series of enormous geoglyphs etched into the desert in Peru, is still a subject of debate among experts.
The disappearance of the Minoan civilization from the island of Crete around 1500 BC is a puzzle that has yet to be fully solved.
The existence and location of the city of Atlantis, mentioned by the ancient Greek philosopher Plato, is still a topic of speculation and debate.
The identity of the ancient Egyptian pharaoh who ruled during the time of the biblical story of Moses is a subject of much discussion among historians.
The mystery of the Antikythera mechanism, a complex and advanced astronomical calculator found in a shipwreck off the coast of Greece in 1901, still fascinates scientists.
The purpose and significance of the Carnac Stones, a series of Neolithic standing stones in Brittany, France, remains unclear.
The true identity and story of the Terracotta Army, a collection of life-sized terracotta sculptures discovered in China in 1974, is still a subject of ongoing research and speculation.