Lowell R, Massachusetts Hall A, Cabot N, Dunster K
Eliot O, Canaday F
Winthrop K, Leverett F, Adams C
Wigglesworth H, Quincy E, Lionel A, Straus D
(Except for Lowell R, all of these entryways are so situated that they can be seen by passersby without a Harvard ID. Winthrop K really is a detached white house that faces Memorial Drive, separate from the rest of Winthrop House; it appears to be in disuse now, but a sign identifying it as K-entry of Winthrop House is still visible from the street on the door of the building.)
The letters of these entryways spell RANK OF KFC HEAD. This clues COLONEL, which is the answer to the puzzle.
Thanks to David Speyer for photoshop assistance.