Obelisk of Montecitorio

Stand still for a moment and listen. Scooters hum past on the edge of the square. Footsteps click across the paving stones. Somewhere a door opens and closes at the palace in front of you, where Italian lawmakers go about their day. And above all of it rises a single shaft of red granite, its surface pitted and worn. It has watched this city for over two thousand years. Before that, it stood in Egypt for centuries more.

This is the Obelisk of Montecitorio. Romans also call it the Solar Obelisk, and that name is the first clue to its strange career. It was not brought here only as decoration. For a time, it was part of one of the largest scientific instruments of the ancient world. It worked as the pointer of a giant sundial, laid out across the ground of ancient Rome.

But let us begin at the very start. The stone was cut from granite in southern Egypt and raised at Heliopolis, the ancient city of the sun god, near modern Cairo. It was made for the pharaoh Psammetichus the Second, who ruled in the sixth century before Christ. Look closely at the faces of the shaft. You can still see carved hieroglyphs, the sacred picture writing of Egypt. Some panels are sharp. Others are badly worn, the result of fire, collapse, and long burial.

The obelisk came to Rome because of Augustus, the first Roman emperor. He brought Egypt under Roman control after defeating Cleopatra and Mark Antony. To celebrate that victory, he shipped two obelisks across the Mediterranean around 10 BC. This was an enormous task. Moving a solid granite needle of this size required a specially built ship and huge teams of workers. One obelisk went to the Circus Maximus, the chariot racing track. The other came here, to the Campus Martius.

The Campus Martius was the Field of Mars, a wide open plain outside the old city centre. Augustus used it to show off his new order. And here is the first surprise. The obelisk was the gnomon of a vast sundial or meridian — the upright pointer that casts the shadow. Its shadow fell across a paved area marked with bronze lines and letters. As the shadow moved and changed length through the year, it showed the passing of the seasons.

We know about this partly from the Roman writer Pliny the Elder. He described the instrument in his encyclopedia of natural history. He also recorded something wonderful. By his own time, decades later, the sundial was no longer accurate. Pliny offered several possible reasons. Perhaps the ground had shifted. Perhaps the sun's course had changed. Even the ancient Romans struggled with the maintenance of their great machines.

There is also a modern theory that is worth knowing, but it is only a theory. In the twentieth century, a German archaeologist argued that the whole design was tied to Augustus himself. He suggested that on the emperor's birthday, the shadow pointed toward the Ara Pacis, the Altar of Peace, which stands not far from here. Other scholars have disputed the idea. It remains a debate, not a fact — but it shows how much meaning Romans may have built into stone and light.

What happened next is a familiar Roman story. As the empire faded, the city shrank. The obelisk fell, possibly through fire or earthquake, and it broke into pieces. Over the centuries, layers of earth and new buildings covered the old ground of the Campus Martius. The great sundial disappeared from sight. Houses and workshops rose on top of it, and most people forgot it had ever existed.

The fragments were rediscovered beneath buildings in this neighbourhood during the Renaissance and the eighteenth century. Raising them again was another matter. The pieces were cracked and damaged, and for years they lay waiting. Finally, Pope Pius the Sixth decided to restore the monument. In the 1790s, his architect reassembled the shaft and set it up here, in front of the palace. To repair the missing sections, workers used granite taken from another ancient monument, a column raised for an earlier emperor.

Now look at the very top. The obelisk is crowned by a bronze globe on a spike. This was the papal restorers' own touch, and it continues the old idea of the sun. Then look at the base. Here you can find Latin inscriptions. One records the dedication made by Augustus, who gave the obelisk as a gift to the Sun after Egypt came under Roman power. Other lines honour the pope who raised it again.

Next, lower your eyes to the ground of the piazza itself. This is the second surprise, and many visitors walk straight over it. A line is set into the pavement, running out from the obelisk. It was added during a modern restoration of the square. It is a gentle reminder of the obelisk's first job. Once again, at least symbolically, the stone points to the movement of the sun across the city.

The building behind the obelisk is Palazzo Montecitorio. It is the seat of the Chamber of Deputies, the lower house of the Italian Parliament. The great Baroque sculptor and architect Gian Lorenzo Bernini began the palace in the seventeenth century, and it was completed by others after him. So here, in one view, you have a pharaoh's monument, an emperor's trophy, a pope's restoration, and a modern democracy at work. Few places in Rome stack so many eras so neatly.

As you stand here, notice the colour of the stone in the changing light. In the morning it can look almost brown. In the late afternoon it warms to a deep rose. Then follow its shadow across the square, just as Romans once did. Perhaps glance down at the line beneath your feet. When you walk on toward the Pantheon or the shops of the old centre, remember that the street level you stand on hides another Rome below — and that this granite pointer once told that older city the time of year.