Admire Sree Padmanabhaswamy Temple, the richest temple in the world, famous for its treasure contained in six underground vaults. The origins of the ancient temple complex remain unknown, with some structures dating back to the 15th and 16th centuries. Still not completely explored, the temple vaults are estimated to contain more than $22 billion in gold and precious jewelry. Non-Hindus aren't allowed inside the temple, but you can still view the historic complex from the outside.