The Liberty Bell is a symbol of the American Revolutionary War, and, by extension, freedom and independence generally. At the time of The Price of Liberty, it was on display at Independence Hall in Philadelphia, Pennsylvania.
The bell was stolen by Robert Meyer and placed in a truck rigged for explosion. Steve Austin and Neils Lindstrom were tasked with defusing the bomb on the truck to prevent the loss of the object and their own lives.
Liberty Bell at Wikipedia