Andrew Price has shared a Blender tutorial on creating a subway in 20 minutes.
I heard that trying to copy a reference photo is one of the best learning exercises, and valuable things to have in your portfolio. I found this reference on Pinterest and decided to copy it using Blender, rendered in Cycles.
All materials are from Poliigon, but the walls and ceiling stucco I made myself using Substance Designer.
Here are some more final and WIP shots: