1. Gursky, whose work tends to feature high vantage points and scenes that produce horizontal bands of color, has taken some of the most expensive photographs ever sold. Among those are his 99 Cent II Diptychon, a shot of the shelves of a 99-cent store, and Rhein II, a photograph of the Rhine River with humans and buildings digitally edited out.

2. (1635) The painting shows a scene from the Book of Daniel in which the king of Babylon, Belshazzar, uses the loot his father Nebuchadnezzar stole from the Temple in Jerusalem in order to throw a feast. During the feast, God's hand appears and writes a prophecy on the wall predicting Belshazzar's downfall—a vision that frightens the onlookers in the painting as well, one of whom is spilling a goblet in horror. The Hebrew letters in the painting are based on a font created by the Dutch rabbi Menasseh ben Israel, but are written top to bottom instead of right to left.

3. (1560s) The fall of Icarus is not the central image in this painting; the mythological youth's legs stick out of the water, barely noticed, near a large ship and a fisherman at the bottom right. Most of the painting depicts everyday scenes in the Netherlandish countryside, such as a farmer driving a horse while plowing his field and a shepherd staring up at the sky while attending to his sheep. In the distance can be seen a city with a harbor, which the ships in the painting appear to be sailing towards. The painting is famously depicted in W. H. Auden's poem 'Musée des Beaux Arts,' whose title derives from the Brussels museum where the painting is held.

4. (1942 - 1930s) According to André Breton's 'Surrealist Manifesto,' Surrealism is 'pure psychic automatism, by which one proposes to express, either verbally, in writing, or by any other manner, the real functioning of thought'; inspired by the work of psychologists Sigmund Freud and Carl Jung, Surrealists sought to represent an unseen world of dreams, subconscious thoughts, and unspoken communication. Similar to metaphysical painting and Dada, Surrealist works are not meant to be clearly understood — they are meant to puzzle, challenge, and fascinate by means of confusing titles, unusual arrangements of reality-based subjects, and abounding contradictions. Painters associated with the Surrealist movement include Salvador Dalí (The Persistence of Memory, Swans Reflecting Elephants, Metamorphosis of Narcissus), Joan Miró (Dog Barking at the Moon, The Tilled Field, Harlequin's Carnival), René Magritte (Time Transfixed, The Treachery of Images, The Son of Man), former Dadaist Max Ernst (Two Children Are Threatened by a Nightingale, The Elephant Celebes), Frida Kahlo (Self-Portrait with Thorn Necklace and Hummingbird, The Two Fridas, The Little Deer), former metaphysical painter Giorgio de Chirico (whose stark color contrasts and veristic style strongly influenced surrealist painting), and Yves Tanguy. Surrealist sculptors included Alexander Calder (Lobster Trap and Fish Tail, Flamingo), Meret Oppenheim (Object), and Alberto Giacometti (Woman with Her Throat Cut, L'Homme qui marche I). The Spanish filmmaker Luis Buñuel created a number of films in the surrealist style, collaborating with Dalí on Un Chien Andalou (An Andalusian Dog) — which Roger Ebert called the 'most famous short film ever made' — and L'Age d'Or (The Golden Age).

5. First shown in 1931, The Persistence of Memory is probably the most famous surrealist painting. The landscape of the scene echoes Port Lligat, Dalí's home. The ants, flies, clocks, and the Port Lligat landscape are motifs in many other Dalí paintings, and the trompe l'oeil depiction of figures is typical of his works. It currently belongs to the MOMA; its 1951 companion piece, The Disintegration of the Persistence of Memory, hangs at the Salvador Dalí Museum in St. Petersburg, Florida.

6. Born Andrea di Pietro della Gondola, Palladio designed villas in and near Venice, including the Villa Rotonda and Villa Barbaro. He integrated Greco-Roman ideas of hierarchy, proportion, and order with contemporary Renaissance styles. His Four Books on Architecture from 1570 relates his theoretical principles. Among architects heavily influenced by Palladio were Inigo Jones and Thomas Jefferson.

7. (1867 - 1941) An American known for crafting Mount Rushmore in the Black Hills of South Dakota. He is also known for The Mares of Diomedes and an unfinished (and later replaced) tribute to Confederate heroes on Stone Mountain in Georgia.

8. (1631) Leyster was a female artist whose entire body of work was once attributed to Frans Hals. The painting's two subjects are a woman sewing by candlelight and a man touching her right shoulder and offering her coins. Unlike in Vermeer's The Milkmaid, the foot warmer in this painting is part way under the woman's skirt, indicating that she is married, but potentially interested in a suitor. Despite this, the woman appears to be ignoring the man's romantic advances.

9. Pop Art parodies (or perhaps reflects) a world in which celebrities, brand names, and media images have replaced the sacred; Warhol's series of Campbell's Soup paintings may be the best illustration of this. Like the object itself, the paintings were often done by the mass-producible form of serigraphy (silk screening). Also like the subject, the Warhol soup can painting existed in many varieties, with different types of soup or numbers of cans; painting 32 or 100 or 200 identical cans further emphasized the aspect of mass production in the work. The same approach underlies Warhol's familiar series of prints of Marilyn Monroe, Jacqueline Kennedy Onassis, and other pop culture figures.

10. Construction began on One World Trade Center, alternatively known as 1 WTC and the Freedom Tower, in 2006, and was the main part of the project of rebuilding the World Trade Center following the 9/11 attacks as part of an overall plan for the site developed by architect Daniel Libeskind; it occupies the former site of the original 6 WTC. The building reaches a symbolic height of 1,776 feet, and is adjacent to a pair of memorial reflecting pools marking the foundations of the original Twin Towers. The new WTC complex includes a transportation hub designed by Spanish architect Santiago Calatrava. A new Two World Trade Center will likely not be completed until 2024.

11. (1850 - 1931) An American who created The Minute Man for Concord, Massachusetts and Standing Lincoln for the Nebraska state capitol, but who is best known for the seated statue in the Lincoln Memorial.

12. Guernica was a Basque town bombed by the Germans during the Spanish Civil War in April 1937. Picasso had already been commissioned to paint a mural for the Spanish Pavilion at the World's Fair, and he completed his massive, black, white, and grey anti-war mural by early June 1937. Picasso's Cubist approach to portraying the figures adds to the sense of destruction and chaos. Guernica was in the Museum of Modern Art (MOMA) in New York until 1981, when it was returned to the Museo Nacional Centro de Arte Reina Sofia in Spain.

13. While Les Demoiselles d'Avignon and other Cubist paintings represent an extension of Paul Cézanne's division-of-space approach to the canvas, Mondrian's De Stijl works are a still further abstraction, such that the canvas is often divided up into rectangular 'tile patterns,' as in Composition with Red Blue and Yellow. The painting simultaneously echoes the bright lights of a marquee, resembles a pattern of streets as seen from above, and creates a feeling of vitality and vibrancy, not unlike the music itself. This work can also be found at the MOMA.

14. (1916 - 1925) Deriving its name from a nonsense word that literally means 'hobby horse' (supposedly chosen by stabbing a knife into a dictionary), Dada was an anti-art movement in Zurich, Cologne, Berlin, Paris, and New York that rejected artistic and social norms in order to protest the establishment. Fervently opposed to the useless slaughter of World War I, Dadaists rejected conventional methods of representation and exhibition: they abandoned oil and canvas, often did work on glass, and accepted 'readymades' (commonplace objects selected and exhibited as works of art) as valid art forms. Dada works often relied on location or accident, such as if a glass should shatter, the artist would hail the accident as an enhancement or an achievement brought about by chance; much like many other abstract artists, Dadaists favored artistic concept over execution. The foremost proponent of Dada was Marcel Duchamp, whose readymades include Fountain, L.H.O.O.Q., Prelude to a Broken Arm, and Bicycle Wheel, in addition to the aforementioned non-Dada painting Nude Descending a Staircase, No. 2. Duchamp's piece The Bride Stripped Bare by Her Bachelors, Even (The Large Glass), consists of two panes of glass with materials such as lead foil, fuse wire, and dust, and utilizes chance procedures; when the glass broke in a shipping crate and received a large crack, Duchamp left the cracks intact, incorporating the 'accident' into the piece. Other key Dada artists include Jean Arp (Cloud Shepherd, Shirt Front and Fork), Man Ray (Lampshade, Le Violon d'Ingres), Raoul Hausmann (Mechanical Head (The Spirit of Our Time), Kp'erioum, ABCD (Self-portrait)), Hannah Hoch (Cut with the Kitchen Knife through the Beer-Belly of the Weimar Republic), Francis Picabia, and Hans Richter.

15. (1917 - 1920s) Also known as neoplasticism, De Stijl (Dutch for 'The Style') was founded in Amsterdam in 1917 and sought to create paintings that were completely abstract, with no references to nature whatsoever. De Stijl paintings are typically set on a white background, use black lines to shape rectangular spaces, use only black and the three primary colors (red, yellow, and blue), contain no modulation, and use only perpendicular lines (diagonals are forbidden). While the movement's theories were outlined by Theo van Doesburg (Neo-Plasticism: Composition VII (the three graces), Composition decentralisee, Composition in Gray (Rag-Time)), the principal practitioner of De Stijl was Piet Mondrian (Broadway Boogie Woogie, Victory Boogie Woogie, Tableau I, Composition II in Red, Blue, and Yellow, Lozenge Composition with Red, Black, Blue, and Yellow); other De Stijl painters include Vilmos Huszar and Bart van der Leck. De Stijl also manifested itself in the architectural works of Gerrit Rietvald (Schroder House, Red and Blue Chair), Robert van't Hoff (Villa Henny), and J. J. P. Oud (Gallery house at Weissenhof Estate).

16. The Guggenheim Bilbao opened in 1997 and is — like its sister institution in New York — less famous for its collection than its building, a Frank Gehry design that seems to be an abstract sculpture all its own. Richard Serra's The Matter of Time is permanently installed here.

17. Located in Amsterdam, this is the national museum of the Netherlands. Currently housed in a Gothic Revival building designed by PJH Cuypers and completed in 1885, its most distinguished works include Rembradnt's Night Watch, Franz Hals's The Merry Drinker, and Jan Vermeer's The Milkmaid.

18. Painted in 1911, I and the Village is among Chagall's earliest surviving paintings. It is a dreamlike scene that includes many motifs common to Chagall, notably the lamb and peasant life. In addition to the two giant faces—a green face on the right and a lamb's head on the left—other images include a milkmaid, a reaper, an upside-down peasant woman, a church, and a series of houses, some of them upside-down. I and the Village is currently housed at MOMA.

19. The son of architect Eliel Saarinen, Eero was born in Finland but spent most of his life in the U.S. and died in Ann Arbor, Michigan. He designed many buildings on the campuses of MIT and Yale, as well as Dulles International Airport in Washington, D.C. and the TWA terminal at John F. Kennedy Airport in New York. Saarinen may be best known for designing the Gateway Arch in St. Louis, though he died before it was completed. Many of his works are characterized by elegant, sweeping forms, such as the Kresge Auditorium at MIT.

20. He studied under Samuel Morse, who popularized the daguerreotype in America, and became a portrait photographer in New York. When the Civil War broke out, Brady saw it as a potential source of memorabilia, and took photos at Bull Run in a mobile darkroom. His work expanded to hiring out crews of photographers to cover the entire war, essentially creating the practice of photojournalism. Brady himself took portrait photos of prominent figures of both sides.

21. Made a series of Untitled Film Stills, consisting largely of self-portraits posed in the style of a B-movie actress, which began a series of photos in which she modified popular photographic forms to respond to the stereotyping of women in the media. Her later series Fairy Tales and Disasters began including mannequins and prosthetic limbs, which she also used as the subject of her 'Sex Pictures.'

22. Sullivan did not design the first skyscraper, but did become a vocal champion of skyscrapers as reflections of the modern age. Though most associated with Chicago, his best-known work is the 1891 Wainwright Building in St. Louis. His partnership with Dankmar Adler produced over 100 buildings. Later works, such as the Babson, Bennett, and Bradley Houses, reflect an organic architecture distinct from that of his one time employee Frank Lloyd Wright. Sullivan's dictum that 'form should follow function' strongly influenced modern architecture; his writings helped break the profession from classical restraints.

23. (1378 - 1455) A Florentine sculptor and goldsmith who taught both Donatello and Filippo Brunelleschi. He is best known for two pairs of bronze doors on the Florence Baptistery (associated with the Duomo, or Florentine Cathedral). He produced a single, low-relief panel to win a 1401 competition (defeating Brunelleschi) for the commission to design the 28 panels for the north doors. After that, he was given another commission to design ten panels for the east doors. This latter work, by far his most famous, was dubbed the 'Gates of Paradise' by Michelangelo.

24. (1660s) This portrait, whose unknown subject is not actually laughing, acquired its common title after being moved to the Bethnal Green Museum in Britain in the 1870s; before that, it was simply known as Portrait of a Man. The painting's subject is dressed in fine black clothing appropriate to Calvinist sensibilities of the Dutch Republic, wears a giant white collar, has a prominent upturned moustache, and is 26 years old according to an inscription at the upper right hand corner.

25. When it opened in Chicago, Illinois in 1973, the Willis Tower was the tallest building in the world, with a height of 1,450 feet. The building was originally (and is still commonly) known as the Sears Tower, as it was built as a new headquarters for Sears, Roebuck & Co.; it was officially renamed after the insurance company Willis Group Holdings, Ltd., in 2009. The building's design, inspired by a pack of cigarettes, consists of a three-by-three set of 'tubes' of varying heights. The tower contains a 103rd-floor 'Skydeck' from which as many as four U.S. states (Illinois, Indiana, Wisconsin, and Michigan) are visible on a clear day, and which also contains several glass balconies that extend out from the building, allowing visitors to look straight down to the street below.