What's inside the Statue of Liberty?

The Statue of Liberty is located on Liberty Island in New York City. It was a gift from the people of France in the year 1886. The tablet in her right hand is the declaration of independence. The statue was designed by Frederic-Auguste Bartholdi using a method called Repoussé. This involved making a life size plaster model first and then hammer copper sheets around it. The support structure was designed by Gustave Eiffel -

What's inside the Statue of Liberty?