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 Mark Twain Cave Mark Twain Cave — originally McDowell's Cave — is a show cave located near Hannibal, Missouri, U.S.. It is the oldest operating show cave in the state, giving tours continuously since 1886. Along with nearby Cameron Cave, it became a registered National Natural Landmark in 1972, with a citation reading "Exceptionally good examples of the maze type of cavern development". The cave — as "McDougal's Cave" — plays an important role in the novel "The Adventures of Tom Sawyer" (1876) by Mark Twain and was renamed in honor of the author, a Hannibal native. Geologically Mark Twain