"My Last Duchess" is a poem by Robert Browning, frequently anthologised as an example of the dramatic monologue. It first appeared in 1842 in Browning's Dramatic Lyrics. The poem is written in 28 rhyming couplets of iambic pentameter.
The poem is preceded by "Ferrara:", indicating that the speaker is most likely Alfonso II d'Este, the fifth Duke of Ferrara (1533-1598), who, at the age of 25, married Lucrezia di Cosimo de' Medici, the 14-year-old daughter of Cosimo I de' Medici, Grand Duke of Tuscany, and Eleonora di Toledo.
Lucrezia was not well educated, and the Medicis could be considered "nouveau riche" in comparison to the venerable and distinguished Este family (Alfonso II d'Este's remark regarding his gift of a "nine-hundred-years-old name" clearly indicates that he considered his bride beneath him socially). She came with a sizeable dowry, and the couple married in 1558. He then abandoned her for two years before she died on 21 April 1561, at age 17. Although there was a strong suspicion of poisoning, it is more likely that the cause of her death was tuberculosis. . It is speculated that the rumor of poisoning was started by enemies of Alfonso II.
The Duke then sought the hand of Barbara, eighth daughter of the Holy Roman Emperor Ferdinand I and Anna of Bohemia and Hungary and the sister of the Count of Tyrol, Ferdinand II. The count was in charge of arranging the marriage; the chief of his entourage, Nikolaus Madruz, a native of Innsbruck, was his courier. Madruz is presumably the listener in the poem.
The other characters named in the poem - painter Frà Pandolf and sculptor, Claus of Innsbruck - are fictional.
The poem is a representation of male and female relationships and their contrasting powers or lack thereof. Women in the past and even in some cultures today are considered pieces of property. Within many religions and cultures, the male bestows a position of dominance and control over women, which constricts their right of free will. During the mid 1800s, a daughter was married off to gain more power, land, allies, and even to gain access to prestigious bloodlines. The duke in this poem uses his power to control a woman, his duchess, by using her as currency. 
The poem is set in the Italian Renaissance. The speaker (presumably the Duke of Ferrara) is giving the emissary of the family of his prospective new wife (presumably a third or fourth since Browning could have easily written 'second' but did not do so) a tour of the artworks in his home. He draws a curtain to reveal a painting of a woman, explaining that it is a portrait of his late wife; he invites his guest to sit and look at the painting. As they look at the portrait of the late Duchess, the Duke describes her happy, cheerful and flirtatious nature, which had displeased him. He says, "She had a heart - how shall I say? - too soon made glad..." He goes on to say that his complaint of her was that "'twas not her husband's presence only" that made her happy. Eventually, "I gave commands; then all smiles stopped together." This could be interpreted as either the Duke had given commands to the Duchess to stop smiling or commands for her to be killed. He now keeps her painting hidden behind a curtain that only he is allowed to draw back, meaning that now she only smiles for him.
In 'My Last Duchess' the Duke of Ferrara is addressing the envoy of the Count of Tyrol. Although he is on his best behaviour, the Duke of Ferrara demonstrates many narcissistic tendencies as he recalls the time he shared with his now-deceased Duchess. Even in death the Duke wished to hide her away behind the curtain where no other man could admire her beauty. The Duke then resumes an earlier conversation regarding wedding arrangements, and in passing points out another work of art, a bronze statue of Neptune taming a sea-horse by Claus of Innsbruck, so making his late wife but just another work of art.
In an interview, Browning said, "I meant that the commands were that she should be put to death ... Or he might have had her shut up in a convent."