My Last Duchess is a Victorian dramatic monologue written by Robert Browning.The speaker is a duke, maybe Alfonso II of Ferrara, a nobleman during Renaissance. The monologue is set in the duke’s castle in Ferrara. The listener that doesn't reply to the Duke is a messenger of another noble family. 

The intelligent reader should focus his attention on two key words in the title: "my" and "last". The adjective "last" implies that there will be no other women after the "Duchess"; the adjective "my" gives an additional meaning to the title suggesting the idea of a possesive attitude of the man to his wife. The word “Duchess” is a reference to the social status of the characters .The reader's attention is also drawn by the subtitle "Ferrara": it may be the setting. 

Even if the poem seems to be about the Duchess,the Duke reveals more about himself than the relationship with his wife. He is a weak and jealous man, whose individualism, as the insistent presence of the personal I confirms ("my last Duchess", "I call", "I said", "I have", "but I", "ask me",...) led to his wife's murder. 

What makes the poem in some way ironic is that the Duchess did not do anything wrong. Her "faults" were her courtesy to those who served her ("She thanked men") and her delight in simple pleasures ("too soon made glad, too easily impressed") that the Duke could not understand ("I know not how"). She did not reserve her attention only for him and his power and it explains why the Duke felt "as if she ranked my gift of a nine - hundred - years old name".

The reason why he killed his wife is now clear to the reader: he could not possess her.

The use of language is very significant in the dramatic monologue.

The rhyme scheme is regular (AABBCCDD) and the structure is circular. 

Last but not least the intelligent reader will realize that there are multiple points of view in the poem: the speaker, the listener, the Duchess and the reader.

In conclusion the reader will manage to comprehend that the monologue is not about the "last Duchess", as he could aspect from the title, but it is focused on the Duke.