The Statue of Liberty is made of thin copper sheets that are about the same thickness as a penny.
They were hammered into the correct shapes in France, transported by ship to America, and riveted to an iron framework created by French engineer Gustave Eiffel, who later built the Eiffel Tower in Paris.
When copper rusts, or tarnishes, it turns a bluish green.
In the early 1980s, it was discovered that the Statue of Liberty had deteriorated so much that a major restoration was required.
The torch and much of the internal structure were replaced when the statue was closed from 1984 to 1986 for the restoration.