Underneath Easter Island

Everyone knows about the iconic and mysterious heads that litter the landscape of Easter Island off the coast of South America, but not many people know much else...For one, the statues are not just heads, but full statues that extend deep beneath the surface...
http://www.mentalfloss.com/blogs/archives/106129

Another little secret is the island's caves, originally carved by lava flows, and suspect-idly inhabited by islanders to hide from raids and slave drivers...
6 km of tunnels discovered in Easter Island

Also, check out the Easter Island Statue Project
http://www.eisp.org/