The One Ring is destroyed in Mount Doom in J.R.R. Tolkien’s mythology.
Mount Doom, also called Orodruin in Tolkien’s invented languages, is a volcanic mountain in Mordor. The Ring was originally forged there by Sauron, and its destruction requires it to be returned to the same fire. This makes Mount Doom more than a dramatic destination: it is the specific place whose fires can undo the Ring.
Frodo and Sam reach the mountain after crossing Mordor with Gollum. Frodo claims the Ring for himself at the Cracks of Doom, but Gollum bites off Frodo’s finger and falls into the fire while holding the Ring. The destruction breaks Sauron’s power and causes the collapse of his realm.
Mount Doom is sometimes confused with other famous peaks in Middle-earth, including Mount Gundabad and Mount Mindolluin. Those mountains have important locations and histories, but neither is the place where the One Ring was forged and destroyed.