[quote=@AmongHeroes]
[@Eru Iluvatar]-On your sheet, I noticed you described your fortification in detail. Am I also allowed to basically "create" my stronghold's features? I wasn't sure how much control the individual players had in that respect.
[/quote]

In these circumstances, where there is no canonical evidence as precedent, it's best to just make stuff up. 

In the case of something like the Black Gate or Minas Tirith, however, I'd say stick to the facts as much as possible.