As a child, Twain went by the name of Samuel Clemens. He lived in Hannibal from 1839 to 1853. The signature was found in July but wasn't verified by scholars until now.

The caves were an inspiration for his work The Adventures of Tom Sawyer. (Zack Kucharski/The Gazette) A look at one of the 260 passageways that comprise the Mark Twain cave in Hannibal, Mo., in 1946.

In this Aug. 6, 2019 photo provided by David Leaning Samuel Clemens' signature is seen inside the Mark Twain Cave in Hannibal, Mo., Clemens' boyhood home.

HANNIBAL, Mo. — Mark Twain made this cave famous through his writings, and speculation swirled for decades that he’d signed his name somewhere inside it. This week, the owners of the cave can ...

Mark Twain Cave Signature In this Aug. 6, 2019 photo provided by David Leaning Samuel Clemens' signature is seen inside the Mark Twain Cave in Hannibal, Mo., Clemens' boyhood home. Experts say it ...

Hannibal, Missouri, is a perfect weekend destination that celebrates the life and literature of Samuel Clemens, AKA Mark Twain. You can also find other notable historic sites, plenty of events and ...

Mark Twain Cave is part of an attraction complex that includes Cameron Cave, Missouri’s newest show cave. Cameron Cave is toured by lantern and flashlight, much like Tom Sawyer would have.

In winter 1819, a natural entrance to a cave was found just south of Hannibal, Mo. One of its visitors in the early 1840s was a young resident who was fascinated by what he saw.

Mark Twain made this cave famous through his writings, and speculation swirled for decades that he’d signed his name somewhere inside it. This week, the owners of the cave can finally confirm ...

Samuel Clemens’ signature is seen inside the Mark Twain Cave in Hannibal, Mo., Clemens’ boyhood home. Experts say it is almost certainly an authentic signature made by Clemens during ...

Mark Twain made this cave famous through his writings, and speculation swirled for decades that he’d signed his name somewhere inside it. This week, the owners of the cave can finally confirm ...

In this Aug. 6, 2019 photo provided by David Leaning Samuel Clemens’ signature is seen inside the Mark Twain Cave in Hannibal, Mo., Clemens’ boyhood home. Photo Courtesy David Leaning via AP ...