Amaranta would sigh, laugh, and dream of a second homeland of handsome men and beautiful women who spoke a childlike language, with ancient cities of whose past grandeur only the cats among the rubble remained. (One Hundred Years of Solitude, tr. by Gregory Rabassa)
The preposition phrase seems like having a small clause [or a verbless clause]. But it’s not easy to identify which is the subject and which is the predicate. And I wonder why ‘of’ is there –– when there isn’t ‘of’, can’t the phrase make sense?
([(1) with ancient cities][(2) of whose past grandeur][(3) only the cats among the rubble remained]: The first bracket seems to be modified by relative clause (2+3). (2) is the subject and (4) the predicate.)