Chancellery, Constables Palace, Marshals Palace and Admiralty

[ichi]

and IIRC you can build one of each

ichi

[ajaxfetish]

I actually started a thread on this subject just a day or two ago. I know about the titles, which aren't bad, but I still don't know if they provide any other benefits. Same for a lot of other specialized buildings.

[Procrustes]

I believe that these four give you a title that you can award to a general - the title will come w/ a star or two and possible loyalty, acumen, etc. I don't know if you can build two of these buildings, but you can own two if you happen to capture or bribe one. However, you only get to award the title once.