It's a diorama. A train just happens to run through it, that's all

what about a church with a grave yard or the delapitated building with a few freshly dug graves in the garden . Maybe a place thats overun with Zombies , limbs and stuff missing. Games Workshop do some skeleton warriors you could adapt for the church.

If your looking for buildings, you might want to try plastruct.com

welcome to the fourm!
now oversized doirama eh? well; i think i can help my "oversized dio" is four 4X8 sheets of 1/4" plywood it dipicts a 1/72nd scale WWII canadian airbase, military, shipyard and of course a town my and my buddys have been working on it for probably 3years now and it has planes from the americans, canadians,russians,germans,brits and many more! as for you mystery/ crime scene dio i cant hel you out but id thought id mention that your not alone in the world of large scale modelling!!
so good luck and i know for sure people here will beable to help (im not the most reliable!) welcome to finescale!