Hello again.
I've found a bigger map of the fortification and it includes the surrounding city and roads, the river and a hornwerk plus ravelin to the North.

biggerMapBurgosCastle.jpg

Now it's going to be easier to cross-reference the heightmap.

Also, I've found some images of a model of the castle in the period 1808-1812, that will help in the modeling of the original castle ("Donjon" in the map), here they are:

modeloftheKeepBurgosCastle.jpg
View from North to South

modeloftheKeep2BurgosCastle.jpg
View from East to West

modeloftheKeepBurgosCastle3.jpg
View from South to North

I couldn't find any view of the model from West to East.