The details kit, very simple to assemble, but no, you don't get the building pictured on the box with it.
I used orangish-rust coloured craft paint and Vallejo Rust Texture, along with Vallejo's black wash to weather the vents.
All 37 pieces from the Walthers Rooftop Details kit, after assembly and rusting and weathering. I haven't put all of them onto my industry, as it would be ridiculously crowded on the roof if I did, but I did use quite a few pieces on it. The extras can go on other structures.
Here's the industry still sitting on my workbench. I've added some vents and exterior rusty piping running below the 3rd storey windows. Difficult to see in this view, but there are several vents on the roof as well. I've also randomly blanked out many of the windows with blue and white fibreglass inserts (decal trim film actually).
I've placed a couple of 60 foot high cubes and an SD38 onto the spur to give me a better idea of the way things might look once I get this re-build finished up.