Mary's attic
because they didn't not that there were some area that wre unexplored.
An intricate combination of paths or passages in which it is difficult to find one's way or to reach the exit.
A labyrinth is a maze, particularly underground or covered.A complicated irregular network of passages or paths in which it is difficult to find one's way; a maze.An intricate and confusing arrangement
Maze would be a good one because it shows complicated passages
If unexplored land was explored then it would no longer be unexplored land, and that is why it is impossible to explore unexplored land.
A synonym for "maze" is "labyrinth." Both terms refer to complex networks of paths or passages that can be difficult to navigate. While "maze" often implies a puzzle or challenge, "labyrinth" can also evoke a sense of intricate design and beauty.
Unexplored is an adjective.
A sentence using 'unexplored' would be: Long ago Michigan was unexplored. Mary's attic is so full of things that it has remained unexplored for many years.
In the sentence "Lost in the labyrinth the knight struggled to find a way out of the dungeon," the word "labyrinth" is a noun. It is used to describe the intricate maze or network of passages the knight is lost in.
An unexplored area inhabited by one's enemy may be called hostile territory.
Besides 'maze', the word 'labyrinth' would fit. A 'warren' can be used to ever to a network of burrows such as those dug by a community of rabbits of bilbies.
The only area that was still unexplored in 1828 was Patagonia