The City College of New York

Numerous reports since the 1920s of students seen -- and recognized by students, and [former] professors years back -- known to have died in the First World War, haunting one of the former political club lounges in Shepherd Hall. Legend had it that in one particular instance, a math tutor noticed that a student's clothes seemed somewhat dated for the mid-20s and put it in his mind to inquire as to how the young man was making out financially; given it was still a wholly free college with a mostly working class student body.

Only later that night did this "absent minded professor" wake up from sleep with a start, scaring his wife in the process [isn't that always the case?], with the recollection that the young man died in France in 1918. Apparitions dressed in 60's & 70's clothes and one ghost in particular is in grunge attire, he always appears "sad looking", is only seen just before or after closing hours.