Mark Twain Memorial Bridge (1936) Mark Twain Memorial Bridge (1936) The Mark Twain Memorial Bridge was a Cantilevered Through Truss Bridge carrying US 36 over the Mississippi River. It was replaced in 2000 with the extension of I-72 and subsequently demolished. The bridge, which replaced motor vehicle use of the Wabash Bridge, was opened in 1936 by President Franklin D. Roosevelt and entered Missouri at the foot of Cardiff Hill which appeared in Twain's books The Adventures of Tom Sawyer and The Adventures of Huckleberry Finn. A crosswalk crossed the highway, connecting the Twain boyhood home with the lighthouse at the top of the hill.
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