Ancient humans, though considered ancient, were far smarter than we could have ever imagine. Every day new science is revealed showing of accomplishments that humans can’t even do today.

Their focus and attention to the smaller things proved they had an innate knowledge of whatever they pursued. Whether astrology, architecture, or something more magical, the ancients were good at what they did.

Here are 15 of the most mysterious ancient structures in the world, and the mysteries they left behind.