Not a museum for model trains, but a model of a real railroad museum.
I got this idea a few years back from an MR article on moving the V&O forward in time, one step which involved removing the turntable and replacing it with diesel facilities.
I thought, why not keep it and make it a museum? Clean bricks, fresh paint, add a modern wing, parking, snack bar, lawns, picnic tables, etc. Out back you could have a workshop with a caboose under restoration, and a dead track with future display items in various states of decay. Taking it a step further, you could run weekend excursions on museum equipment, and even have it serviced at the modern shops.
I'm sure someone's done it, but I haven't seen it yet. Seems like almost a required element for a club layout. A good way to put vintage equipment on display without it feeling out of place.
Mac B.