The title of refers to a woman who is likely to be the subject of the poem. It is strongly marked by the possessive “My” that may imply a relationship between the speaking voice and the woman he’s referring to.
The adjective “last” may suggest that she’s passed away.
The word “Duchess” tells the reader about the lady’s social status, however it does not provide other information about her age.
As for the structure of the poem it is organized into one stanza.
The speaking voice addresses a silent listener and tells him about his late wife, the Duchess. He describes her portrait, which is hidden behind a curtain. The speaking voice first focuses on her wife’s expression and glance.
The poem refers to the duke’s jealousy because of his wife’s nature.
The poem is closed by the speaking voice’s invite to the listener to follow him downstairs, where another nobleman is waiting for him. However, the Duke openly reveals that he is only interested in the man’s fair daughter.
The poem is an example of dramatic monologue: the speech is pronounced by a first person speaking voice who addresses a silent interlocutor. The speaking voice provides the reader hints of the listener’s presence by interacting with him.
Despite his possessive nature, the Duke’s relationship with her late wife is characterized by detachment: the speaking voice talks about himself in third person and uses the expression “her husband” to make her and the memory of her look more distant. He addresses her with “my last duchess” in the opening of the poem and later only with the pronoun “she”: he never mentions the woman’s name.
The poem conveys the Victorian mentality, marked by a strong patriarchal and sexist view of the world. In the Victorian Age, a woman was subdued to the power of her father and of her husband. Therefore, the idea of a woman who resembles the Duchess was unacceptable: her flirtatious and cheerful nature were strictly repressed by the Man.