Here's a little experiment with randomly generated maps based on this post at the blog Renaissance Woodsman.

I wrote a little javascript doodad to take a list of rooms (mapped to the cards in a deck of cards), arrange them according to the rules outlined in the blogpost above, and then render them as an image.
I wanted the generator to be entirely self-contained, so it uses only unicode characters and simple geometric shapes. Here are a couple randomly generated example castles:

Click image for larger version. 

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Click image for larger version. 

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And here is the standalone html file with the generator.