<human>:  What is the history behind the Liberty Bell symbol?
<bot>: The Liberty Bell is an iconic symbol of American independence. According to popular legend, it was cast in 1751 in the British foundry of Pass & Stow of Philadelphia for the Pennsylvania Assembly. Its purpose was to commemorate the 50-year anniversay of William Penn's 1701 Charter of Privileges, the document that established Pennsylvania as a free and sovereign entity. The bell was rung on July 8th, 1776 to mark the signing of the Declaration of Independence, and later became a symbol of the abolitionist movement.