Mareilon was one of the ancient cities united by Entharion the Wise to form the Kingdom of Quendor in 1 GUE.
Mareilon was destroyed in 773 GUE when the Endless Fire was burned for 4 weeks.
The destruction of Mareilon caused Lord Dimwit Flathead to issue a series of 5,521 edicts that severely limited access to magic, and incidentally, lawyers.