1943 steel cent coins. The copper cents differ from their steel counterparts in four ways: In an error similar to the 1943 cents, a few 1944 cents were struck on steel planchets left over from 1943. There are two explanations given for why this happened. One explanation is that steel planchets were left in the press hopper and press machines from the previous year mixed in with copper planchets. Another explanation credits the error to the production of 25 million Belgian two franc pieces by the Philadelphia mint after that country's liberation from the Nazis. These coins were of the same composition and
Metal roof Metal roof A metal roof is a roofing system made from metal pieces or tiles characterized by its high resistance, impermeability and longevity. It is a component of the building envelope. Zinc, copper and steel alloys are commonly used. Copper has played a significant role in architecture for thousands of years (see: copper in architecture). In the 3rd century B.C., copper roof shingles were installed atop the Lovamahapaya Temple in Sri Lanka. The Romans used copper as roof covering for the Pantheon in 27 B.C. Centuries later, copper and its alloys were integral in European medieval architecture. The copper roof