This is the type of mosaic that I love to see submitted to the Mosaic Atlas. Polly Price sent this photo of a mosaic on a railroad trestle in Atlanta (Hill Street, SE between Decatur St. and Martin Luther). It looks like it's been around for quite a while and I would imagine that hundreds of people drive by it every day but never even notice it. I wonder what its history is.
A larger photo can be seen here in the Atlas. Look on page 3.