Art Institute of Chicago audio guide,
five stops, free.

Back up first. The canvas is over two metres tall and more than three metres wide, and it only assembles itself from a distance. Then come in close and the whole park breaks apart into separate dots and dashes of colour that never blend. Both views are correct. That was the argument.

Georges Seurat worked on it from May 1884 to March 1885, put it away, and went back to it from October 1885 to May 1886. He was in his mid-twenties. It went up in May 1886 at the eighth and last Impressionist exhibition, and again that August at the Salon of the Société des Artistes Indépendants, a group he had helped found two years earlier.

It looks like an idle afternoon by the river. Seurat did not think of it that way. He told the critic Gustave Kahn that his model was the Panathenaic procession on the Parthenon frieze, and that he wanted to make the moderns file past in their essential form. Which is why almost nobody in it is moving.

Find the woman with the bustle at the right edge, and follow her arm down. There is a monkey on a leash. Seurat added it two years into the work, along with several other figures, including a man carrying a rolled newspaper so far back among the trees that most visitors never find him.

Now compare the sunlit grass in the middle with the grass at the edges. The middle is browner. Seurat used a new pigment there called zinc yellow, and it began darkening in his own lifetime and has gone on since. The sunshine at the centre of this painting is fading in slow motion.

Look at the edge of the canvas too. That band of dots around all four sides is painted. In 1889 Seurat took the picture off its stretcher, folded out the tacking margins, primed them and painted a border, so that the eye would have a transition between the picture and the wall. The white frame around that was made by the museum's own framers and put on in 2022, after a year of research into the flat white mouldings Seurat preferred. They built it almost entirely by hand, because the canvas is not quite rectangular. It is very slightly trapezoidal, and the frame is contoured to follow the painted edge exactly.

It is here because of two Chicagoans. Frederic Clay Bartlett and his wife Helen Birch Bartlett bought it in 1924, with this museum in mind, three years before the French state acquired its own first Seurat. Helen died of cancer in October 1925, and the following May her husband gave their collection to the Art Institute in her name. Three of the five paintings on this walk still carry her name on the label.

It has left the building once. In 1958 it travelled to the Museum of Modern Art in New York, and on the fifteenth of April a fire there killed one person. This canvas was hanging on a floor above the flames, and it was carried out into the Whitney Museum next door.

Stephen Sondheim and James Lapine spent several days with this painting before writing Sunday in the Park with George, which opened on Broadway in 1984 and took the Pulitzer Prize for Drama the year after. It was the first time Sondheim had seen it in the flesh. And when Cameron Frye stands in front of a painting until it dissolves in Ferris Bueller's Day Off, filmed here and released in 1986, this is the one.

Start at the bottom left, with the wooden rail cutting across the corner. Toulouse-Lautrec put it there to keep you out. You are not at the table. You are behind it, and the evening began without you.

The Moulin Rouge opened in 1889 and became the most famous of the Paris café-concerts, the places people went to drink and watch a show. Toulouse-Lautrec was there constantly. He had a table permanently reserved for him. The owner of the club had bought one of his paintings, Equestrienne, to hang in the lobby, and that canvas is in this museum too.

Nobody in this picture is invented. Around the table are the dancer La Macarona, the photographer Paul Sescau, the writer Édouard Dujardin, the vintner Maurice Guibert, and, turned away from you with the flaming red-orange hair, the dancer Jane Avril. Standing behind them, the dancer La Goulue is fixing her hair.

Now find the artist. In the middle background there is a short man in a dark hat walking beside a very tall man in a top hat. The short one is Toulouse-Lautrec. The tall one is his cousin, the physician Gabriel Tapié de Céleyran. He painted himself into his own party at the size he actually was, next to a relative who towered over him.

Then look right, at the very edge of the canvas. A face rises out of the dark, cropped by the edge of the canvas, lit from below, painted an acid green that no skin has ever been. That is the singer May Milton. The Moulin Rouge was designed around electric light, which was new and hard and unlike anything faces had been seen in before, and Toulouse-Lautrec seized on what it did to them. The green is not symbolism. It is a lamp.

After his death the painting went to Maurice Joyant, the executor of his estate and co-director of the Galerie Manzi-Joyant in Paris, then on through Paul Rosenberg and the London dealers Reid and Lefevre, until Frederic Clay Bartlett bought it and gave it to the Art Institute in 1928. It first went up on a wall here on the twenty-third of December 1930, and May Milton has been staring out of the right-hand edge of the room ever since.

Two metres tall, nearly three metres wide, and the first surprise is that there is no rain in it. Search the canvas for a raindrop and you will not find one. The weather is carried entirely by the umbrellas and by the shine on the cobbles, and some critics in 1877 complained about precisely that.

The place is real and it is still there. This is the crossing of the rue de Turin, the rue de Moscou, the rue Clapeyron and the rue de Saint-Pétersbourg, in what is now the Place de Dublin, in the eighth arrondissement, a short walk from where Gustave Caillebotte lived. His paintings of Paris almost never leave the streets he used every day.

This is Haussmann's city, still new. Napoleon the Third had put Georges-Eugène Haussmann in charge of rebuilding Paris in the 1850s, a project that ran for decades and cut about 137 kilometres of boulevards through the old town, pushing thousands of mostly working-class residents out to the edges. Caillebotte paints the result: clean stone, wide pavements, and 24 people who are not looking at one another. Most of them are comfortably off. Behind them there is a maid, two cab drivers, and a house painter carrying a ladder.

Look at the green lamppost. It splits the canvas down the middle and fixes the depth of everything behind it. Then look at the couple in front. They are walking straight into you, and they are watching something outside the frame that you will never get to see. The cropping is photographic, and Caillebotte was working in the years when photography was becoming ordinary. Most scholars think he traced his preparatory drawings from photographs; a technical investigation by this museum in 2015 argues instead that he used a camera lucida. There are 23 surviving studies, most of them working out where to put people.

He showed it in April 1877 at the third Impressionist exhibition, which he had helped pay for and organise out of his inheritance. The reviews were split: some praised the precision, others complained that the rain was invisible, that the umbrellas and the lamppost and the cobbles were all too exact. Then it disappeared. It was not seen in public again until a memorial exhibition in June 1894, after his death, and then it hung in a Caillebotte family house, essentially unknown, for another sixty years. Walter Chrysler junior bought it in 1954. The Art Institute bought it from the dealer Wildenstein in 1964, when Caillebotte was remembered mainly as the rich friend who collected and funded the Impressionists. That purchase is the main reason he is now counted as one of them. The museum did not even settle on this title until 1991.

Before you leave, the lower left corner, in greyish-brown paint: G. Caillebotte, 1877.