Enclosures attached to the house?

I've been thinking...one way to help my favorite crazy cat(see this thread http://www.thecatsite.com/forums/sho...d.php?t=118308) is to attach an outdoor enclosure to the house. Since she lives in the basement, its ground level & one window is just perfect. There's a retaining wall there. It's about 20' long & 10' out from the house.

Any ideas on how I could build a kitty enclosure there? She could easily climb the retaining wall, so I'd need to make it so she couldn't.

The things I've thought about are:
purrfect fence(I don't know it it'll work in this area)
a chain link dog kennel with a top
an enclosure with chicken wire that has a top

I want to be 100% sure she cannot get out, & I also want to be sure the outside kitties cannot get into it. Which makes things a little more difficult. I'm thinking about opening the window for her to come & go whenever I'm in the office watching Ophelia at first. If it's a completely enclosed enclosure, then she could come & go as she pleases. Is there any way for me to install a cat door in the window? It slides open sideways if that makes sense.

Any ideas would be great, it's still snowy here, although the snow should melt soon with the temps. I can't take her out on harness & leash as if the leash touches her, she panics. I've tried working with her on that & she doesn't get used to it.

Natalie, I just saw this thread. I have pictures of my enclosure that I(well my DH did most of the work) built off my front porch. My window goes up and down and we created a cat door with this window. You could probably attach something very similar to what we did. I will try to post you a few pictures in the morning. We are also fixing to start another enclosure off my bedroom window into the back yard.

I am using Hissy (MaryAnn) thread on her enclosure as a guide line for our second room.

Thanks! I still plan on building the enclosure, even if Ophelia isn't staying here. It'll likely be months before anyone adopts her....

I have an enclosure off a window and I used chicken wire. I don't like the chicken wire it is weak and seems to break easy and I think I will have to replace it this year or next.

I would not use chicken wire or gamebird wire if there is a choice.
I have watched cats chew through the stuff pretty quickly.