While many buildings on campus are clearly inspired by medieval forebears, they remain contemporary interpretations--the real thing is obviously not possible. Although it's true that the Tribune Tower downtown has fragments of stone from medieval cathedrals embedded in its walls, they are seriously decontextualized; even much of The Cloisters in New York might legitimately ask if the medieval can be razed and rebuilt. Fortunately, much that is medieval remains in manuscript form, available here in the library and, increasingly, in online digital facsimiles.
Special Collections in Deering Library has several manuscripts and musical scores available. There is an unfortunate misconception that items in Special Collections are somehow reserved for "serious scholars," e.g. faculty, grad students, research assistants, etc. While many of the items are, indeed, rare and valuable, the truth is that they are available to ALL members of the Northwestern community. Primary source materials have the advantage of having been there--they are direct links to people, places and events that have shaped history, and are yours for the asking.