I agree, it's not bad for a virgin terrain.
You should focus on the foreground at first, try some better looking grass and make sure the shrubbery transitions better. The ferns for instance are extremely green in comparison to the saturated grass.
So yes, work that out. Try to match the colors, but don't make it obviously monochromatic.
Secondly, you could work out something a tad bit more interesting than a flat wall behind the gates. Try giving it some depth and show some form of city contours fading in the fog.
Could definitely liven up the imagery.
Lastly, you seldom reach a fine result without playing with light and light sources. You have a few options here, the lanterns for instance. You could also try to brighten up the sky.
And while we're on light, you should try to spread the eerie fog better, they kind of clump together now looking like lumps of gray smog.
