Myth Drannor was not the floating city, is was crushed beneath a floating Netheril city that was dropped on top of Myth Drannor.
In regards to the OP, Myth Drannor has a LOT of information, but here is the condensed version...
Hundreds of years ago (before Silverymoon was a big factor) Myth Drannor arose in the forests of Cormanthor and was a major elven kingdom and center of power. It drew the attention of a demonic horde that destroyed the city and the kingdom. It became a demon infested ruin and sad reminder of the fall of elvenkind in Forgotten Realms.
Fast forward to the years before the Spellplague and Myth Drannor was refounded by the elves and reclaimed after a terrible battle against the demons. (There is a series of novels written about these events that are a decent read, nothing great, but not bad.)
Following the rise of New Netheril, Myth Drannor was once again destroyed and there is not much left of the city after the Netherese dropped one of their flying cities atop Myth Drannor.
Again, that is a VERY condensed version of what your looking at. There was an old 2E book about the fall of Myth Drannor that contains a wealth of lore on the kingdom that is a very interesting read. There is also the books about the rise of Myth Drannor again and then the newer series in which it is destroyed once more. Personally, I was extremely disappointed that WotC decided to allow the city to be taken out again. I feel like it reeks of RETCON, but I also dislike everything that happened to the Realms after the release of 4E and the ridiculous Spellplague. I'm glad to see that 5E has gone back to the classic roots of the Realms.
This is the 2E produce of Myth Drannor that Lyrel was talking about. It is a great book, and might give you some good ideas for your character to try and remake a Knightly Order of the past. Good luck.