My neighbor purchased an outbuilding and it sits on the property line (mostly on my property), what can I do?

When I came home to find it, I knew it was close to the property line, but I didn't think anything else about it at the time. About a month later, I went out and found my property lines, and sure enough, about 80% of his building is in my yard. I told him it needed to be moved at that time. Six months later, the building has still not been moved. So I mentioned it again, he told me he didn't have the money, but assured me it would be moved within another month or two. Well that time has almost expired. I was told I could go pay a lawyer to draw up some papers to "legally" serve him with a notice that the building has to be moved, but personally, I don't like the idea that I have to go spend my money to make him move it when it wasn't my mistake. Any suggestions?