This 1955 photo by American fashion photographer Avedon features the first first evening dress designed for Christian Dior by his new assistant, Yves Saint-Laurent.

This 1989 image by American artist Prince is a “re-photograph” appropriated from a cigarette advertisement.

This 1919 photo by American artist Stieglitz is one of the many pictures he took of American painter Georgia O’Keeffe (whom he later married).

This 1919 photo is another one of the more than 350 images that Stieglitz took of O’Keeffe between 1918 and 1925.

This 1925 photo by American artist Weston is one of many nude photos he took throughout his career.

This 2009 photo of a Siberian kremlin (fortress) was taken by Russian president Medvedev and sold at a charity auction.

This tintype image from , taken in Fort Sumner, New Mexico, is the only authenticated photo of the famous Old West outlaw.

American artist Sherman examines the role and representation of women in her work. Like most of her photographs, this 1985 image depicts the artist in costume and make-up.

This pictorialist photo from 1904 shows a forest across a pond, with part of the moon appearing over the horizon in a gap in the trees.

This 1997 photograph by German artist Gursky is an example of one of his large scale landscape photos, often taken from high vantage points.

This two-part 1999 photograph depicts the interior of a supermarket, with aisles full of colourful products. The photo is digitally altered to reduce perspective.

This photograph from the same series gives a better look at the amount of detail that Gursky is working with.

This 1992 photomontage by Canadian photographer Wall shows a a group of Soviet soldiers talking to each other after being killed in the Soviet-Afghan war in 1986.

This 1981 image is another one of Sherman’s many conceptual self portraits.

This 1999 photo was part of a set of 6 images depicting the Rhine River in Europe. Gursky used digital editing to remove extra details, such as dog walkers and a factory building.

This 1999 photo by Australian artist Lik depicts the Antelope Canyon, in Arizona.

Write two brief paragraphs. In the first, explain which of these photographs you think deserves to be the world’s most expensive – and explain why. Give at least three reasons (you can discuss composition, elements & principles, historical significance, and your own personal opinion). In the second paragraph, explain which of these photographs you think is least deserving of being one of the world’s most expensive. Give at least two reasons.