Elvangar (Forgotten Legacy #6‪)‬

Long ago when Angragar was the shining light of the human world, elves and humans were allies and trading partners, but that was centuries ago. When the elves ended their siege of the ancient human city, they enshrouded it in an impenetrable jungle and left caretakers to hide it from prying eyes. Now Angragar has awakened, and elves have appeared among the humans.