The National Gallery of Victoria sits on the long, leafy boulevard of St Kilda Rd in Melbourne. Its stony exterior mimics the army barracks nearby but the interior is alive with art. The most spectacular painting in its wonderful collection is a huge work by Giambattista Tiepolo, the last of the great line of Venetian Renaissance painters.

The Banquet of Cleopatra transports us, not to Egypt but to Venice. East meets West in a painting that has it all: history, romance, legend and high style. It has all the extravagance of grand opera, which also had its beginnings in Venice.

Tiepolo had tremendous assurance. He was the last in the line of great Venetian painters that extends from the Renaissance of Giovanni Bellini through Giorgione, Titian, Tintoretto and Veronese into the 18th century.

At the end of this long tradition, all painterly problems are solved perfectly. The space of the work is completely convincing, from the tiled floor that leads into it to the blue distance of the sky. The extravagantly dressed figures are arranged in a tellingly dramatic way and the colour has a magnificence that is part of the Venetian heritage. The whole composition is focused on Cleopatra and, more than that, on a single pearl she is about to drop in a glass of wine or, as some say, vinegar.

This visual opera has a well-known plot. The life and death of Cleopatra has always been great subject matter for artists. As ruler of Egypt, she was considered the most dangerous threat to the Roman Empire since the invasion of Hannibal.

The details of her life and loves have been the subject of drama, story and film, usually beginning with her liaison with Julius Caesar. Her most passionate relationship was with Mark Antony, which ended in defeat at the sea battle of Actium.

This led to the double suicide that made them immortal in history and literature. Their love was written about by Plutarch, writing in Rome soon after the events. Shakespeare drew on Plutarch for his play Antony and Cleopatra, turning prose into immortal verse and creating in Cleopatra a character of "infinite variety".

Roman writer Pliny the Elder added to her legendary status by telling how when she first met Antony she gave a banquet. When Antony said the meal had not cost much she wagered she could double the expense easily. She did so by taking one of her earrings, a pearl of immense price, and dissolving it in vinegar before drinking it.

It was the legend of this lavish banquet that fascinated Tiepolo and he painted several versions of the story. There is one in the National Gallery in London and another in Stockholm. Tiepolo brought his immense skill and authority to the task of painting huge decorative paintings. He did vast frescos in Wurzburg in Germany as well as in Spain but he was a Venetian through and through.

Much of his work in Venice was religious but he did one big secular work there about Cleopatra.

One of the wealthiest families in Venice, the Labia, commissioned him to decorate a room in their palazzo on the Grand Canal. He painted the ballroom in brilliant perspective in such a way that the walls seemed to dissolve into a panorama of sky, architecture and the splendour of noble figures. Even today, when the frescoes have faded, it is difficult to tell the real doors and windows from the painted architecture within which the meetings, banquets and farewells of Antony and Cleopatra are told. He crowded the scenes with all the details of Venetian life: nobles, servants, dwarves, musicians, soldiers and domestic pets.

The paintings in the Palazzo Labia, because they are done in fresco, which is painted directly into the wet plaster of the walls, have faded a little. The huge painting in Melbourne has retained its vivid colour because it was painted in oil, although the composition is almost the same as the similar subject on the walls in Venice.

The work in Melbourne is a symphony of blue, orange, red and russet colours all keyed to the bright white of the tablecloth at the centre.

The painting shows Antony and Cleopatra seated at a table where Cleopatra has welcomed the great Roman conqueror with a feast. Vividly clothed servants are clearing away the remains of the first part of the meal. The wager has been made. Cleopatra has taken one of the twin pearls of her earrings, worth millions in the currency of the time, and is about to dissolve it in a glass of vinegar and drink it. Realistically she would have had to crush it first, and it would have taken awhile to dissolve, but realism would spoil the story.

Tiepolo does not provide us with profound insight into the characters but he paints an amazing visual spectacle. The scene is filled with black servants, attendants, spectators, soldiers with pikes, a dwarf, a splendid vase and a magnificent hound. In the background is a clear blue Mediterranean sky.

Cleopatra is a Venetian beauty clad in a tight-laced Venetian dress, her face framed by an immense lace collar. Antony, on the other side of the table, has an elaborate plumed, parade helmet as befits a soldier. His strongest feature is his great muscular arm. Across the table is the bizarre figure of Lucius Munatius Planeus, the Roman legate to Egypt who was to judge the outcome of the wager.

The whole work is in many ways a homage to Tiepolo's predecessor, Veronese. The older artist loved to incorporate magnificent hounds into his work and Tiepolo follows suit with a huge hound led by the dwarf and a little lap-dog for Cleopatra.

The colour harmony is special to Tiepolo. It is not as darkly rich as the paintings of Titian or Tintoretto but has a bright, sunlit quality.

The perspective is flawless, taking us deep into the space of the painting. The dramatic moment is conveyed perfectly and the whole is a vision of Venetian beauty even though it is set in Tarsus, near Egypt.

The history of the painting is also romantic. It had been painted for the Elector of Saxony, who ruled one of the minor principalities in Germany. When Napoleon overran Germany, he claimed the painting as loot and took it back to Paris.

He gave it to his Empress Josephine who, after her divorce, took it to her country residence at Malmaison. After the defeat of Napoleon and the death of Josephine, it was bought by Czar Nicolas I of Russia for his royal collection. It ended up in the Hermitage in St Petersburg. After the Russian Revolution, when the Soviets needed money, a number of paintings from the Hermitage were sold. The Tiepolo was bought for Melbourne in 1932 with funds from its rich Feldon Bequest.

It continues to enrich the walls of the gallery in Melbourne alongside two other works by Tiepolo but the banquet is incomparable. It is in its way as magnificent as Shakespeare's glorious play.

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