Hand crafted copper roofs are traditionally known for their beauty and lifetime.  As opposed to steel, copper does not rust.  Copper ages with beauty and protects itself from corrosion with a natural coating of oxidation (patina).  In 3 - 7 years time, the shiny metallic copper turns a musket brown / bronze and eventually patina green.  With the protective patina coating a copper roof can last up to or more than 100 years completely maintenance free.