The Harriet Tubman Underground Railroad National Historical Park is hosting an Underground Railroad walking tour in Downtown Cambridge, Maryland Saturday, April 23 at 1pm. Free. Start at the Harriet Tubman Mural courtyard, 424 Race St. The walk will be led by Ranger Tim of the National Park Service. Discover the stories of the Underground Railroad and the people associated with Harriet Tubman’s life. Wear comfortable shoes and bring a bottle of water.