Pre-historic China is home to some of the most incredible structures that hint at advanced civilizations long before our current historical records begin. Among these are the Yangshan Quarry, the Longyou Caves, and the numerous pyramids scattered throughout China, often shrouded in mystery and suggesting a legacy of pre-flood megastructures. All of these ancient sites and megalithic structures have some kind of machine marks that suggest they were built by an advanced civilization lost to history.