Service hallways in large castles

Several fantasy series I’ve read have castles or other large buildings with extra (smaller?) corridors for servants and/or guards to use so they can move about the castle doing their duties without interfering / interacting with the other occupants of the castle.

I’m curious if anyone has actually mapped something like this.

I’m also curious if anyone has seen a published work with such corridors mapped out.

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Further thoughts:

I haven’t brainstormed this much but one quick adventure that I could see with such corridors would be some sort of castle infiltration adventure. Be it theft, assassination, rescue…the corridors would provide access to various sections of the castle with a bit less chance of being spotted.

I also think that this concept could be used without the corridors fully mapped using theater of the mind. Have rough maps with general areas in place, some notes about the areas, but not precisely mapped. Actually, this method could be used both with and without service corridors for large and complex castles.