Underground Railroad: The Secret History

Retracing the steps of freedom seekers escaping on the Underground Railroad, archaeologists use high tech to explore a Florida fort that was nearly erased from history.

Archaeologists unearth the lost community of Quindaro, Kan., a long-forgotten abolitionist town that shielded Freedom Seekers from bounty hunters, and in Illinois, experts use high-tech tools to explore a secret underground tunnel.

Archaeologists uncover evidence of a Freedom Seeker community in the swampy marshlands between Virginia and North Carolina; in Maryland, experts investigate artifacts that may confirm the location of Harriet Tubman's childhood home.

Maritime routes of the Underground Railroad are traced as an underwater archaeologist searches for the wreck of a Civil War ship used by enslaved people to find freedom; experts reveal waterways to Canada that made liberation possible.