Client's description was just "Tumulus of Bougon", so I took the time to research the Tumulus of Bougon. It's apparently a crypt of sorts, with the actual structure having 5 unique barrows.
desaturated for extra gloom.
Worked up the details in some areas of the structure. Also adjusted contrast between structure and the sky/clouds.
Finished up the foliage and went onto the building structure and sky (clouds). I might go back and add in a few more brick details.
Spent some time creating foliage brushes in Procreate while painting.