Ok, I'm traveling the world, crossing the seas, to find a new spot to build my house (its getting WAY too crowded) and I come across this. Its so big, and looks like someone was working really hard on it. Anyone seen it before?

Nope.

Could possible be a chunk error or a dug out and abandoned build site.

that's a lot of smoothstone D:

Its mined out flip... smoothstone is the natural form of cobblestone. Its all natural, someone just took off the top two or three layers.

its deths, i found it on the world map and questioned him on it

It's Dethmedul's. It's Asgaard. ANd yes, it's legit, he's been working on it since he's joined.

drae, you can see in the picture how it starts a few blocks above ground, and dirt goes down i think 4 or so blocks. the surface of it might be just from the world but the walls are not.

Good for Deth, and it was not 3-4 blocks high, this thing was at least 9. It was big.

It cuts a tree in half