...They have a fairly sizable number of letters and documents online. See the link. There's also a University site with a limited number of photos: University of Notre Dame Archives.
The University of Chicago has a fine collection that you can look at online: University of Chicago Photographic Archive. It has many thousands of historic photos of buildings, grounds, student activities, past visitors (like Mary Pickford!); old pics of faculty, students, staff, administration; and more. That would be a nice model for us to emulate.