Continuing my quest to upload one of my games from https://slashie.net to https://itch.io every week, I have published Ultima Castle Generator there, a procgen tool to generate castles like the ones you would find while roaming the Britannian countryside in Ultima V. Play with it online here.
I made this one for fun back in 2016, following a challenge from the procedural generation reddit. The process I did was based on examples, checking the maps from the game in order to dissect their structure. You can still find them here
The generator works in three steps, as described in this blog. An intermediate step subdivides the space into utility rooms, which are then filled based on their utility. The source code can be found here in case you want to play around with it a bit.
The version at itch.io features some simplifications in the UI to make it look simpler and cooler, similar to the great generators by watawatabou. The legacy UI was kept at slashie.net including the intermediate generation steps.