Tashkent's museum of railway engineering is open air with 13 old steam, 18 diesel and 3 electric engines. We spent an hour wandering through the museum photographing old trains.
For a photographer this museum shows much more than just trains; it shows that you need something in the photo to show scale. The old Soviet era engines are huge, without a person in the photo, there is no way to appreciate how large the engine and wheels are.
With a person in the photo, you can see the scale.