List some of the significant locations/settings in The Picture of Dorian Gray.

It is useful to consider setting in The Picture of Dorian Gray in terms of how it displays the theme of duality—the contrast between good and evil, morality and immorality, and purity and decay. 

One clear example we have of this is the hidden location of the picture itself. From its creation by Basil, the picture is associated with the desire to remain hidden and secret. Basil expresses his reluctance to display the painting publicly...

It is useful to consider setting in The Picture of Dorian Gray in terms of how it displays the theme of duality—the contrast between good and evil, morality and immorality, and purity and decay. 

One clear example we have of this is the hidden location of the picture itself. From its creation by Basil, the picture is associated with the desire to remain hidden and secret. Basil expresses his reluctance to display the painting publicly as it contains too much of himself, referring presumably to his fascination with Dorian. 

Later, when Dorian himself notices the first signs of decay appearing on the painting, he hides it in the attic behind a curtain, permitting it to be seen by no one but him. The dark, dusty attic highlights the perverse delight that Dorian takes in his secrecy, contrasting with the rich, decadent, and perfumed settings so prevalent in the novel.

In chapter 11, Dorian is described as creeping up to the attic to view his flawless face in the mirror in contrast with the decayed face of the painting. He relishes the ability to indulge his vices hidden from the view of society and to maintain the look of "one who kept himself unspotted from the world."

In the same chapter, Dorian's delicately scented chamber is juxtaposed with "the sordid room of the little ill-famed tavern near the Docks," which he only ever frequents in disguise and under a false name. Public Dorian is fresh-faced, perfumed, and spotless—a dandy, certainly, but still able to use his beauty as a mask of innocence. In private, though, in the sordid little room in a seedy area of town and hidden behind the curtain in his own attic, Dorian indulges his vices with no thought to the consequences, thus displaying the duality between Dorian's angelic persona in public settings and the decrepit, decaying reality secreted behind a curtain.