Pre-Adamite race (ruins)
Antarctica used to be tropical.
Barron Trumps Marvellous Underground Adventure is a documentary.
Underground entrances exist in asia as well.
Underground cities, many extra-terestrials races. Some of them claim to be terrestrials but you would have to ask the bird and the lizards yourself to decide.
Stay away from the Tall White's children if you value your life.
You think Halo is a game?
There's more 'coincidences' in the 'story' than you could imagine.