Interesting article from Historic England's latest blog. Only covers England though- "Over the centuries soldiers and Prisoners of War (PoWs), have created personal and expressive art on the places where they lived or served. These murals, cartoons and graffiti were often subversive, humorous, risque, nostalgic or decorative. Some were tolerated by military authorities in the interests of morale, and others were officially sanctioned. Many of these fragile images are in abandoned or semi-derelict buildings on former airfields and other military sites, subject to erosion and decay and much has been lost. However, some examples have been preserved and fully documented, and a handful have been removed for display in museums and other sites. Such art offers important visual traces of the past, unlocking clues to the original use of buildings, and revealing intimate insights into military lives, longings and preoccupations in wartime Britain." War Art: Military and Civilian murals from the Second World War
It was a kick in the butt the first time I got the ... big picture. Those GIs must be thirty feet high.