Command block gate for underground base

This is another project made by me.
I am submitting this for thoose, who want to make underground base, but who don't know how to correctly use command blocks.
It is ready hidden enterance base built in ground.
It has a round shape entearnce, trought which you can access underground.
I ask you to modify this map, but only in one way- under enterance is a small hub room. You might dig a 3x3 hole in center of it, put ladders(or stairs) and make way down. When you are deep enaught(about layer 20 or whatever you wish), build there your base. You can builid anything you wish...
Good luck:)

P.S. In screenshots you can see it with LB photo realism 128x texture pack...