Mark Twain three of his siblings survived childhood: Orion (1825–1897), Henry (1838–1858), and Pamela (1827–1904). His sister Margaret (1830–1839) died when Twain was three, and his brother Benjamin (1832–1842) died three years later. His brother Pleasant Hannibal (1828) died at three weeks of age. When he was four, Twain's family moved to Hannibal, Missouri, a port town on the Mississippi River that inspired the fictional town of St. Petersburg in "The Adventures of Tom Sawyer" and the "Adventures of Huckleberry Finn". Slavery was legal in Missouri at the time, and it became a theme in these writings. His father was an attorney
Mark Twain Cave routes within the cave, construct a small building near the entrance for ticket sales, and advertise the cave in newspapers as "Mark Twain Cave". One cold winter day in 1925, Judge Cameron's son Arch was caring for the family's cattle herd when he noticed steam rising from a sinkhole in the ground across the valley from Mark Twain Cave. After some digging a large natural underground room opened up. Further exploration found a cave even larger than Mark Twain Cave, with more twisted pathways. This "sister" cave was named for the Cameron family, and is Missouri's newest show cave. Tours