I've got a short (2 high 4x4) retaining wall around the pond that I want to
remove temporarily.

So I go out this morning full of **** and vinegar, thinking I'll put my pick
under it and will it loosen right up. Well I wiggled some body parts loose,
but not much luck with the wall. Next, came the big guns, long heavy 2"
steel pipe. I could bend the pipe at will, but the crappy little retaining
wall did not budge. :-(

So I'm wondering if a farm jack might be a better approach to getting it
out, preferably in good shape.

Any ideas?