Elven-halls

A name given to the great underground dwelling and fortress of King Thingol of Doriath, built during the long years when Middle-earth lay under starlight and Melkor was held imprisoned in Aman. Devised and built by the Dwarves at Thingol's request, the Elven-halls of Menegroth, the Thousand Caves, spread out beneath the forests of Doriath in the middle of Beleriand. Entered by a stone bridge across the river Esgalduin, their gates led down into a network of intricately and ingeniously carved chambers. The Elven-halls lasted throughout the long remaining years of the Captivity of Melkor, and survived until the closing century of the First Age. They fell after Thingol's death, plundered by the Dwarves and ultimately ruined by the Sons of Fëanor.

Though in practice only Menegroth is explicitly given the name of the 'Elven-halls', the same name might in principle be applied to any of several similar underground dwellings of the Elves, perhaps most notably Finrod's stronghold at Nargothrond. The name is closely reflected by the 'Elvenking's Halls', the dwelling of Thranduil in northeastern Mirkwood, which were indeed inspired by the Thousand Caves of Thingol in Doriath.