I don't know why I never put two and two together, but the city of Cologne and the perfume didn't connect for me until our recent visit.  As it turns out Eau de Cologne is not in fact French, but German.  The formula was originally given as a wedding gift from a Carthusian monk to a young businessman.  He set up shop in Cologne and used the building number "4711" to name the scent.  

This story had come to light before we visited Cologne.  While wandering the city I was thrilled to stumble upon the store which still bottles the original scent.  We had to stop and check it out.  I travel better with Fun Facts at the ready. ; )