When talking about the map of Braavos for TLOIAF, illustrator Jonathan Roberts stated the following on his website:
"yes, look at this one carefully – there are locations on here that haven’t appeared in the books … yet"
In an interview for Quartz, however, Roberts was more specific in saying that he was sent unpublished TWOW material with instructions:
"I was sent a set of chapters from The Winds of Winter [the forthcoming sixth book in the series] in 2012, with geographic details about the city of Braavos which were specifically required to be in the maps to support the plot of the upcoming novel. I do not know what those plot points are, just that they are important."
Since maybe Roberts is not a qualified ASOIAF reader (ie compulsive re-reader / conspiracy theorist), I imagined that he might be refering to something already raised here or on other forum and still have no idea about the role in the plot of what he had draw.
I did my best to identify some of those "geographic details", but I came to the conclusion that I am not such a qualified reader, either. All I could come up with were ten unnamed buildings that stood out from the general landscape (due to the similarity of their features and those of the buildings with names). I reread all the chapters that take place in Braavos, but I could not find a reference to them aswell.
However, since we know of the imminence of an election of braavos and that every year they celebrate the unmasking, it may be that these details have been added to give cartographic support to these events. There is also the possibility that the details are strictly geographical, designed to substantiate the continuity of trade in Braavos even in the midst of the icy winter. I don't really know.
What do you think?