The Liberty Bell cracked in 1846 and has never rung since. Yet few objects in American history have spoken more loudly.

Cast in 1752 and originally hung in the steeple of Independence Hall, the bell bears an inscription from the Book of Leviticus: "Proclaim LIBERTY Throughout all the Land unto all the Inhabitants Thereof." Abolitionists adopted those words as a rallying cry. Suffragists did the same. The irony that the bell sat steps from where George Washington kept nine enslaved people, rotating them out of Pennsylvania every five months to circumvent the state's own abolition laws, is not lost on anyone paying attention.

Today the bell rests in a glass pavilion on Chestnut Street, cracked and still. VoiceMap's self-guided audio tours use it as a lens for the larger contradictions of Philadelphia's founding story, tracing the gap between the ideals inscribed on its surface and the realities that surrounded it.