What should we do with our jungle?

Our back yard looks like a jungle. Ok maybe it IS a jungle. We can tell that once upon a time it was a nice yard. There seems to be the remains of a fern garden and some hostas with a brick outline.

But no one has lived here for several years. It's very overgrown and seems like a big job to us. We aren't sure what to do or, more importantly, how to do it. What can we do ourselves? What should we have someone else do?

So now you can give us some pointers. The yard is all shade and has a lot of ivy. It doesn't have grass but does have some non-ivy ground cover. Here are some pics to get you started!

Oh and that last pic is just for fun. If you look closely you can see a brick building. It is an abandoned, broken down old building that we think was at one time the community pool building! It is actually kind of creepy!