Gondolin was the hidden city of the Elves in J.R.R. Tolkien’s First Age stories. Founded by Turgon, it stood in a concealed valley surrounded by the Encircling Mountains of Beleriand.
The city was established by Noldorin Elves who sought refuge from Morgoth, the first Dark Lord. Its location remained secret for centuries, allowing Gondolin to become one of the great strongholds of the Elves during the wars of Beleriand.
Gondolin was eventually betrayed by Maeglin, who revealed its location to Morgoth. The city fell during an assault involving dragons, Balrogs, and orcs. Tuor, Idril, and their son Eärendil escaped with other survivors, preserving an important line in Tolkien’s mythology.
Gondolin should not be confused with Nargothrond, another important hidden Elven realm, or Doriath, the forest kingdom of Thingol. The story appears in The Silmarillion and is also treated in detail in the posthumously published The Fall of Gondolin.