Clue 1:
This song explores a theme that is also addressed elsewhere in the Maiden catalogue - a notable example of this can be found on the same album as the song you're looking for.
Clue 2:
A contrast is used in the chorus.
Clue 3:
The origin of the song title is related to an area where the song has been performed by Maiden. Maiden's performance there is well documented.
Clue 4:
The song takes inspiration from a book (yeah, I know). In this book, there is a non-human character with a name that appears in other Maiden songs (but not in the song you're looking for). The chorus of the song you're looking for also has a line that nods to what was a working title of the aforementioned book, but the title was changed before publication.
Clue 5:
The song has been performed live by two Maiden vocalist. It is also released on a Maiden live album.
Should we be guessing at all? The Aftermath, The Unbeliever, Paschendale. Sign of the Cross, Seventh Son of a Seventh Son, Dream of Mirrors, The Final Frontier, Lord of Light, To Tame a Land