When fog hid a lighthouse's beacon, sailors needed an audible signal to guide them, so a fog tower containing a bell was often built alongside a lighthouse. Large bells such as the 1,100 pound bell in this tower were used because their sound carried a long distance. Point Lookout Lighthouse and the fog bell tower stood near the treacherous crossroads where the Potomac River meets the Chesapeake Bay, a place where both weather and shipping traffic were tricky. In 1965, the Coast Guard closed Point Lookout Lighthouse and the fog bell tower, and their function was taken over by a steel tower placed offshore. The fog bell tower was then moved to the Museum.