Fontana dei Quattro Fiumi

Listen first. Under the voices and the clink of café cups, there is a steady rush of water. It falls over rough stone and spills into a wide basin. Step closer and you can feel a cool mist on your face, even on a warm Roman afternoon. In front of you, four giant marble figures lean out from a rocky mountain. Above them, a tall stone needle points at the sky. This is the Fountain of the Four Rivers, in the heart of Piazza Navona.

Before we look at the marble, look at the shape of the square itself. Notice how long and narrow it is, with gently rounded ends. That shape is not an accident. Under your feet lies the Stadium of Domitian, built in the first century for athletic contests. The ancient seating became the foundations of later houses. So when you walk around the piazza today, you are tracing the outline of a Roman racetrack.

The fountain belongs to a much later Rome, the Rome of the popes. In the mid-seventeenth century, Pope Innocent the Tenth came from the Pamphilj family. Their family palace stood right here, on this square. The Pope wanted to turn the piazza into a stage for his family's glory. A grand new fountain at the centre was the heart of that plan. He gave the commission to Gian Lorenzo Bernini, the great sculptor of Baroque Rome, and the work was finished in 1651.

How Bernini won the job is a story Romans still enjoy. He was out of favour with this Pope at the time, and other artists were in the running. According to a popular tale, Bernini made a silver model of his design. The model was placed where the Pope would see it, perhaps with help from his powerful sister-in-law, Donna Olimpia. The Pope saw it, admired it, and changed his mind. Treat the details as legend... but the result is right in front of you.

Now look at the four giants. Each one stands for a great river, and each river stands for a continent known to Europeans at the time. The Nile represents Africa. The Ganges represents Asia. The Danube represents Europe. And the Río de la Plata, in South America, represents the Americas. Bernini designed the figures, and skilled assistants carved much of the marble to his plans. Walk slowly around the basin. Each side gives you a different character.

Find the Nile. His head is wrapped in a cloth, so you cannot see his face clearly. Many visitors miss the reason. In the seventeenth century, no European knew where the Nile began. Its source was a mystery. So Bernini covered the river god's head. It is a small sculptural joke about the limits of knowledge — a river whose origin no one could see.

There is a famous story here too, and it is almost certainly untrue. Locals like to say the Nile covers his eyes so he does not have to look at the church across the square. That church, Sant'Agnese in Agone, has a facade by Francesco Borromini, Bernini's great rival. Some say the Río de la Plata also raises his arm, as if the church might fall on him. It makes a good tale. But the church facade was begun only after the fountain was complete. The rivalry was real. The insult in stone is not.

Now look at the Río de la Plata. Near him you will see coins spilling out, a symbol of the silver and wealth Europe drew from the Americas. Look for a strange creature nearby. It looks a little like an armadillo, or perhaps an imagined beast. Bernini had never seen the animals of South America. He worked from descriptions and travellers' reports. The result is wonderfully odd, and very human.

Move on to the Ganges. He holds a long oar, because the great river of India was famous for being navigable. And then the Danube, the river of Europe. He reaches up toward the papal coat of arms. That gesture is a quiet message. The river closest to Rome turns toward the Pope himself. All around these figures, look at the carved plants, a horse bursting out of the rock, a lion drinking, a sea serpent in the water. The mountain is crowded with life.

Now raise your eyes to the obelisk. It looks Egyptian, with its carved hieroglyphs. In fact, it was made in Roman times, during the reign of Domitian — the same emperor who built the stadium below you. It once stood outside the city, on the Appian Way, where it had fallen and broken. Bernini had the pieces brought here and raised. It is a neat circle in history. Domitian's obelisk now stands over Domitian's stadium.

At the very top, look for a small bird. It is a dove holding an olive branch. That dove was the emblem of the Pamphilj family. So above the four continents, above the four great rivers, sits the Pope's family symbol. It is a statement of power, made in marble and bronze. Look at the base too. The obelisk seems to stand on almost nothing. Bernini opened the rock below into a hollow cave, so the heavy stone appears to float above empty space.

The water here also tells a story. For centuries, on hot summer weekends, the drains of the square were blocked. The piazza flooded into a shallow lake. Carriages drove through the water, and crowds gathered to watch and splash. The custom ended long ago. Today the square has three fountains in a row. To the south is the Fontana del Moro, and to the north the Fontana del Nettuno. Bernini's river gods sit proudly in the middle.

Before you go, find a quiet place on the edge of the basin and stay a moment. Watch how the light changes on the white marble as clouds pass. Listen to the water falling over the rough stone. Look past the giants to the curved line of buildings, the old outline of the racetrack. When you walk away, turn back once. From a distance, the four figures blend into one great mountain, with the slim obelisk rising from its heart — and the small dove still watching over the square.