I am considering building an underground "shelter" of sorts in my backyard. Can anyone here give me some advice on building one?

-SS

I pretty much have my dimensions figured out for how long/wide I want it to be, I am more concerned with how deep I should make it and what building materials to use.

Is there anyone out there with a shelter already made that could provide me some insight? I have a basic idea of how I want the structure to go down, I would just like to know other peoples' ideas on their own shelters and what not

Some time ago I read a series of articles concerning the construction of an underground shelter from discarded underground fuel (gasoline) storage tanks. With some research they can be had basically for the cost of transporting them. Then it's a matter of cleaning them out, welding and cutting and the excavation.

what is the purpose of this shelter ? [ what are you hoping it will protect you against ]

what is your budget ?

what is your intended capacity ? [ both inhabitants and duration ]

See my post in response to "crowbars" request on info for a shelter. CONCRETE....may suit your pocket better.
Great ideas can come cheap

Look for a book called "How to build your own underground home" by Ray G. Scott. It's a bit dated (I think it comes from the 80s) but it seems quite thorough. I've never actually tried to build a house, and I've only skimmed the book, but it looks like it should give you at least a starting idea of what you want in a shelter and how to do it. Hopefully a library near you has it.