Some areas I can recognize by geography: single lines on peninsulas, major rail hubs like Chicago or Kansas City, by shape/lines once you know the area, etc.  I can also get a permalink from ORM and put the coordinates into the url for kosmtik.  

However, I was wondering if there was a way to get the ORM background (Mapnik Grayscale) or similar to display behind the renderings from the MML file.  There seems to be quite a few additional plugins for kosmtik but it's a bit confusing as to what they do or how they work.  I've seen ones that will render side by side or over but not under.  Not sure if I'd fully need to render the "world" or if the grayscale tiles could be pulled in from an existing tileserver.

Also, did anyone have any luck working with two sessions of kosmtik?  I can run a second .mml and specify a different port number, but sometimes, the browser, seeing the same url (despite differing port numbers), caches the tiles and requires a hard refresh to get the correct view.  I could probably play around with running the mml files out of a different folder or symlinking them.

Thanks,

Jonathan