The Lonely Mountain, also known as Erebor, is a fictional mountain from J.R.R. Tolkien's Middle-earth legendarium. It is located in the northern part of Middle-earth and is known for its rich deposits of gold and precious gems. The mountain is the ancestral home of the Dwarves of the Lonely Mountain and features a large entrance that leads to vast underground halls and treasure hoards. The mountain plays a central role in Tolkien's novel, The Hobbit, where the character Bilbo Baggins accompanies a group of Dwarves on a quest to reclaim their homeland from the dragon Smaug. The Lonely Mountain symbolizes both the wealth and the dangers that come with greed, as well as the themes of adventure and heroism throughout the story.