This is a classical style portrait of the Empress Elizabeth, consort of the Austrian Emperor Franz Joseph I. One immediately thinks of the Roman empresses, such as the formidable and wily Livia, consort of Augustus (and described by one of her grandsons as 'Ulysses in a frock.') Such an obvious historical reference attempts to associate Elizabeth with the grandeur and timelessness of the Roman Empire.
A second reference is to the ancient, powerful Mediterranean earth goddesses, such as Cybele and Demeter (who is associated with the Empress tarot card). These deities were sometimes depicted as empresses or rulers, a reminder of their absolute authority over the natural cycles of birth, growth, death, and rebirth. The Empress provides a natural counterpoint to the Emperor; he ruling over the affairs of men, she over those of nature. Thus we see both historical and mythological themes merging in Elizabeth's portrait, as several millennia's worth of ideas about female power are distilled in one seemingly simple image.