After seeing u/Inkdarkstone's post on reddit I decided to do a attempt of a concept of a dragon castle/fortress which is builded to counterfight the way of how the dragons fight in the books and what technology they have available.

Welcome at the Taubenschlag castle (Yes I named it Dovecote, but it isn't as weird as a castle's name until you know that there is for example a castle named Bun) found in the tall mountains of the Skywing queendom.

Even tho living in Czechia gives me advantige when it comes to castles, because we literaly have almost 1000 of them and there are two castle ruins just near my hometown, the problem is that they are builded by humans to protect humans against human attacks, which can't be done in this scenario.

Since aside spears and the metalic discs Deathbringer used we didn't seen the dragons use much of other medieval weapons I needed to adapt the architecture to this type of limitations. Only thing which wasn't confirmed in the WoF canon would be the use of buckets with various dangerous liquids for the castle's protection like molted lead or boiling oil/tar.

Another important note is the interior: Since dragons can fly the Taubenschlag castle is builded in a way which forces the attackers to first get up towards the entrance into the main building before needing to descent down into the deepest parts of the castle and the rooms themselves are contructed to be maze-like. A thing you also could notice is the that there is fewer and fewer room the deeper you go. this is mostly due to fact that the walls need to be thicker to hold the weight above them - which doubles as another layer of protection which prevents the attackers to simply break through the walls into another rooms

I also imagine that there would be also a secret passages from the castle for the dragons if all defences fail.

Aside these types of fortresses, I imagine that WoF dragons would more commonly use underground fortresses similar to the Josefov fortress or rock/cave castles like Predjama castle in Slovenia.