Our final stop in Springfield was Lincoln's law office. Its currently closed for renovations but of course one can still walk around the square by the old state capitol building. I've never been able to tour the law offices, primarily because my only other visit was very brief and I stopped here way before it opened (first light actually which was a very cool way to tour the downtown sites).
This view from the presidential library shows a bit of what I imagine they are creating right now. Probably not the diorama aspect but the layput of furniture etc.
Across the street from the law office is the state capitol building that Lincoln would have argued cases in quite frequently.