The Feild HQ Telephone building next to the Strawberry farm at the top of L'Aleval was disgused as a bungalow, down to a piched roof and Chimmney pots. That had a painted window on the outside. Complete with a flower in a pot! Not so much a mural but the ramps down to the Ammunition storage bunkers at Noirmont and the oberservation towers at Mot Orguill castle have superb granite facings. This is real craft work, very out of place really.
Most of teh bunkers had some form of external painted camouflage, or in the case od smaller ones a cladding of local material.