Cloud bands and the scallops in the sky

[Koen G]

The al-Azhar mosque in Cairo. It was built in the late 10th century, which is well on time for Voynich consideration. However, as you also imply, buildings like these evolved significantly over the centuries, and a modern picture probably won't tell us much about what the building looked like to any medieval observer. They got damaged, rebuilt and added to all the time. For example, the first versions of the four current minarets were all built in the late 15th century or later according to the wiki.

It would be very interesting though, to see what this building, or Cairo in general looked like during the middle ages.