A man once infamously said “you can’t explain that” and it turns out there are some things we really can’t explain. These are enigmas and artifacts that have no known orgin or purpose including The Giant Stone Balls of Costa Rica, and the Baigong Pipes
In an area of China not known to ever contain people, let alone industry, there are three triangular mysterious openings on top of a mountain containing hundreds of ancient rusty iron pipes of unknown origin. Some of the pipes go deep into the mountain. Some of them go into a nearby salt water lake. There are more pipes in the lake, and more still running east-west along the lake shore. Some of the larger pipes are 40 cm in diameter, are of uniform size and are placed in what seems like purposeful patterns.
Link
http://skeptoid.com/episodes/4181
Anyway, I don't think these phenomena need to be inexplicable to be incredibly cool. They're still intriguing, beautiful, and bizarre.