Andrea Palladio published his Four Books of Architecture in 1570. He designed villas for wealthy people who lived in and around Venice.
Palladio was one of the earliest Neoclassicists. You don't have to read him very far to find out that he was heavily influenced by Roman architecture, in particular by the only surviving book by a Roman architect, Vitruvius' Ten Books on Architecture.
Palladio's villas were an attempt to recreate Roman style in the 16th century. His books were eventually translated to English and because of them Neoclassicism swept 18th-century England. Thomas Jefferson was a fan, and used Palladio's blueprints as a starting point for designing his home Monticello.
I had gotten the impression that Palladio's books might have given some rules for laying out his villas, but that turns out not to be the case. He does give a whole bunch of floor-plans in Book Two, though, which are quite instructive.
In 1978 Stiny and Mitchell developed a shape grammar by looking at Palladio's blueprints (“The Palladian Grammar,” Environment and Planning B 5). I have not been able to get a copy of this paper so I don't know whether it's worth anything.
Vitruvius's books are interesting in their own right. For instance, the section about where to locate the temples for the various deities is interesting. Apparently the worship of Vulcan involves lots of fire, so you want his temple well outside the city. The worship of Venus involves rites that prove distracting to upright young men, so Vitruvius recommends putting Venus's temple outside the city as well. Near the harbor, if you've got one.
I have turned from whole-city layout to the layout of individual buildings. It seems wiser to work bottom-up from a single piece of gameplay (the burgling of a building) rather than top-down.
My initial steps for randomly constructing a building are not very impressive. I am using an adaptation of the algorithm I used for laying out alleys. The rooms of the house are laid out on a grid. The walls of the grid are then given random offsets. Finally, the random offsets are made to match in either the horizontal or vertical direction (randomly chosen) at each junction, to ensure that rooms don't overlap or leave gaps. Additionally I impose a line of symmetry on the house. Here's what I've got so far:
To ensure that all rooms are connected by doors, I use a breadth-first search to flood-fill connections from the front door. Then I go through and randomly add other door connections.
The problem with the grid-based approach is that it is hard to have rooms that vary significantly in size. For instance, a lot of urban Roman houses have a central courtyard (to admit light) surrounded by a whole bunch of little rooms.
Still, having something is better than having nothing. I'm going to throw in some loot and guard patrols and see how it plays, and then try to think about how to give the houses more realism and character.