Also called The Thousand Caves, Menegroth was a vast underground city from which Thingol and Melian ruled Doriath.
It was built by the Dwarves of Belegost from the Ered Luin for Thingol in the latter part of the Years of the Trees.
There was only one entrance to Menegroth and that was across a great stone bridge on the south bank of the river Esgalduin which cut almost through the heart of the kingdom of Doriath.
Menegroth prospered throughout much of the First Age until in 502 Thingol was slain in his treasury by the Dwarves of Narog. The dwarves sacked the city for the Nauglamír, in which Thingol had the Silmaril set that Beren and Luthien had recovered from Morgoth's crown.
Afterwards, Dior, the son of Beren and Lúthien, and heir to Thingol, briefly settled there with his wife Nimloth until Menegroth was attaked again, this time by the sons of Fëanor for the Silmaril.
(Image this page is 'Beleg Departs Menegroth' by Alan Lee)