Doriath:

The realm of Thingol in Beleriand, Doriath was one of the greatest of the Elf-kingdoms. It was sacked by Dwarves after the death of Thingol. After which Dior Eluchíl, his grandson became king. Dior was slain by the sons of Fëanor and so ended the realm of Doriath. Within Doriath was Mengroth, the underground palace.