Journey to the Center of the Earth (French: Voyage au centre de la Terre, also translated under the titles A Journey to the Centre of the Earth and A Journey to the Interior of the Earth) is a classic 1864 science fiction novel by Jules Verne. The story involves German professor Otto Lidenbrock who believes there are volcanic tubes going toward the center of the Earth. He, his nephew Axel, and their guide Hans descend into the Icelandic volcano Snæfellsjökull, encountering many adventures, including prehistoric animals and natural hazards, before eventually coming to the surface again in southern Italy, at the Stromboli volcano.
As to the novel itself, while unquestionably one of Verne's masterpieces in terms of story, it's probably the one that's aged the hardest of all Verne's works, and almost all of the science in this text has been exploded, modified, or simply changed by the intervening hundred and fifty-odd years of scientific development. Because Verne was in part intending this book to be a source of scientific education, the characters spend a lot of time talking about geology, archaeology, etc., to each other, and since most of that's outdated now, modern readers may want to skip over the more scientific chunks of the book and simply read it as an exploration tale.