Historical settings
Historical times and places in dreams suggest that the content belongs to the collective unconscious.
Becoming unconscious, for example by merging with the masses, represents a regression to the collective unconscious. By merging with the collective, one moves backward in time.
One may also dream of historical places as a recoil when reaching a point in life where the obstacles are too great to continue; one is thrown back in time, perhaps to find a solution to contemporary problems.
The historical place may also represent a timeless place, something that alway is, which again suggests the archetypes of the collective unconscious as opposed to the complexes of the personal unconscious.