The basement under my 1st floor apartment is a rare monster.  It is not just inherently creepy, but also full of spiders and dirt.  The creepiness comes from the fact that it is full of forgotten nick knacks and exercise machines that previous tenants have laid to rest in the filth.  I also believe that there be monsters down there.  According to my friend Al Vargas, they are an issue in Massachusetts and steal your Internets.