The Caragdûr was a black precipice of rock on the north side of the city of Gondolin.
After killing his wife, Eöl the Dark Elf was executed by being flung down the Caragdûr. Just before his fall, Eöl cried out to Maeglin, saying "here may you yet die the same death as I". Many years later, during the Fall of Gondolin, Maeglin had laid hands upon Idril but was forestalled by Tuor. Tuor fought with Maeglin and cast him far out so that Maeglin's body struck thrice upon the slopes of Amon Gwareth. Although Maeglin was not said to have died falling from the Caragdûr, he did share the fate of Eöl in a nearby location.
Other versions of the legendarium
The idea of Maeglin's body striking thrice was included by Christopher Tolkien into his Silmarillion to fulfill Eöl's words, but it was taken from the Lost Tale of "The Fall of Gondolin", which had no premonition nor Caragdûr. That can explain why in the published Silmarillion the deaths of father and son happen in different places.
In later revisions of the Silmarillion, Tolkien considered and rejected the name Caragdar.
- J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Quenta Silmarillion: Of Maeglin"
- J.R.R. Tolkien, Christopher Tolkien (ed.), The Silmarillion, "Quenta Silmarillion: Of Tuor and the Fall of Gondolin"
- Paul Strack, "S. Caragdûr loc.", Eldamo - An Elvish Lexicon (accessed 15 December 2019)
- J.R.R. Tolkien, Christopher Tolkien (ed.), The Book of Lost Tales Part Two, "III. The Fall of Gondolin": "Notes and Commentary", p. 212
- J.R.R. Tolkien, Christopher Tolkien (ed.), The War of the Jewels, "Part Three. The Wanderings of Húrin and Other Writings not forming part of the Quenta Silmarillion: III. Maeglin", p. 325