Qin Shi Huang's tomb

In 1974, farmers in China's Shaanxi province accidentally unearthed one of the biggest archaeological finds of the 20th century — the life-size terracotta armyof Emperor Qin Shi Huang (259 B.C. – 210 B.C.).

The intricately carved figures aren't a mystery: Historians know that the clay army was created to defend China's first emperor in the afterlife. What isn't known, however, is where exactly the emperor is buried or what treasures his burial chamber might contain.

A pyramid-shaped mausoleum is located about a mile to the northeast of where the terracotta army was discovered. However, no one has actually entered the mausoleum that holds Qin Shi Huang's remains.

The first emperor's final resting place is the most opulent tomb ever constructed in China, according to ancient documents describing its construction. An underground palace, complete with a surrounding "kingdom," the mausoleum is made up of a network of caves and even included a state-of the-art drainage system. Whether archaeologists will ever have the technology they need to safely excavate the tomb (which also happens to contain extremely high levels of mercury) remains a mystery, as do the many treasures that lay inside.