When we visited Bursa in October, the mosque at the Muradiye complex was undergoing restoration and renovation. The workers there told us that after removing old paint from the facade, they found older paintings hidden underneath. They are images of the Greek flag, apparently painted on there during a brief period of Greek occupation after WWI, in 1922, and then subsequently covered up after the occupation ended.
It reminded me of the fresco restorations that were done in the Ayasofya a few years back. At the time, they had to remove relatively newer Islamic calligraphy to reveal the older frescoes underneath–ones that depict faces and therefore contradict orthodoxy regarding proper Islamic iconography.
It made me wonder: When history is painted over our world in layers, how do we decide which layers to expose and which to hide? Which ones to destroy, and which to preserve?