I visited my brother in Mankato, MN today. There are some 135 foot tall grain silos in the middle of town, adjacent to the Minnesota River. The City commissioned a renowned artist from Australia to paint a huge mural on the front and back of the silos. It's difficult to imagine how he was able to create such realistic images on such a large scale.
More information on the work is here:
http://www.twinriversarts.org/silo-art-project