I've only visited the Liberty Bell once but that was at a difficult time in my life and in American history. It was just a few weeks after 9-11-2001, and the Bell was under high security and partial lockdown (being only open a few hours a day as I recall). It was so unusual to see armed soldiers standing by the entrance to a National Park Site. Still, I found the sight of the Bell to be inspiring and waited in line to see it.
The Liberty Bell rang in the tower of the Pennsylvania State House (a,k.a. Independence Hall), and became associated with American Independence. The Bell probably developed its crack in the early 1840's after nearly 90 years of use. Metal workers widened the thin crack to prevent its farther spread and restore the tone -- the wide "gap" in the Liberty Bell is actually the repair! A second crack was subsequently to develop and the bell was retired.
The bell weighs over 2000 pounds and is made of 70% copper, 25% tin and small amounts of lead, gold, silver, zinc, and arsenic.
Its inscription, "Proclaim Liberty Throughout All the Land Unto All the Inhabitants thereof", needs to be spread around the country, perhaps now more than ever.