If you are still looking for advice, in a concept, the most important thing is not the painting. Is to figure out what you want to represent. The mood of the place, the history behind it. Is it a ruin? An active temple? Who goes there? Is this temple in this world, dimension? What kind of ceremonies happen there? Etc, etc..
When you have a history, a personality for this place, make a drawing. Black and white drawing, no painting fancy yet. Concepts should work without color before anything. When you have a solid drawing, with persoanlity, good proposrtions and perspective, start painting. Painting will add more awesomeness to what is already awesome.
Keep it up.