This is what some of it looks like.
The Dig-It Dungeon is the secret evil base of the Dig-Its. It is where they plot their schemes, practise their nasty, rotten songs, and build their weapons. It is basically a gigantic dungeon full of dirt that encompasses a large part of Dig-It Land.
It was found by the Dig-Its while they were looking for a place filled with Dig-It resources. They conquered it and claimed it as their own. They first wrote the lyrics to Do They Dig It inside of it back in the year of 1094, and released the aforementioned nasty, rotten song to the world on December 21st, 2012.
The Dig-Its do not want anybody who visits the area to know the truth behind it, and thus they like to disguise it as their own humble abode, and must force the visitor to get out by means of digging it immediately, otherwise they will be forced to death.