Matthew’s virtual tour: the Pantheon and Campus Martius

We’ve encountered the Pantheon as a point of departure in Roman temple architecture, retaining the columnar porch of conventional temple buildings, but adding the huge dome space behind, a radically new experience. The Pantheon sits today at the heart of what was medieval Rome. It survived itself as a church from AD 608 and because of all that later building, it’s hard to get a sense of its ancient architectural context now. So we can use the digital model to take a look. The Pantheon used to stand probably in a porticoed square.

If we zoom out from the Pantheon itself in the area in which it sat, we can start to see its relationship with other neighbouring buildings. The Pantheon as it now exists is rebuilt on top of an earlier Augustan era temple and that corresponded with Augustus’ round mausoleum to the north, the two round structures of maybe about the same size pointing to one another across what was then the open space at the northern Campus Martius, a plain in the loop of the river, full of gardens and temples and imperial cult buildings. And it reminds us of the Pantheon’s link between the emperors and the divine. As the area started to fill up, other temples joined the Pantheon.

Hadrian’s temple, whose surviving wing of columns we’ve seen, stands nearby. Perhaps close to that, a complex dedicated to Matidia, his mother-in-law, and her mother, Marciana, who was the Emperor Trajan’s sister. There was a complex dedicated to the Egyptian goddess Isis nearby too, built or rebuilt by the Flavian emperors after the fire in AD 80. The Flavians had a particular interest in Egyptian religion. There are honorific columns here to Marcus Aurelius and Antoninus Pius, linked to their funerals and their ascent into the heavens as gods. And there are other heavenly monuments in the area, too. Particularly interesting is the Horologium or Solarium Meridian marker of Augustus, built in 10 BC.

And to understand what this building is doing, we have to understand how Roman emperors mediated between heaven and earth. Julius Caesar’s calendars reforms of 46 BC. Were recalibrated by Augustus’s chief priest Pontifex Maximus in nine BC, setting the heavens in order and establishing the emperor as arbiter of the relationship between the heavens and mankind, through a properly regulated calendar. So this sundial, or Horologium or meridian marker, was a monument to this. It was laid out by a mathematician called Facundus Novius and described a few decades later by Pliny and fragments of it have been found in basements in the area.

It consisted of an Egyptian granite obelisk with a bronze marker at its tip and this cast a shadow at noon on bronze lines let into a special pavement, marking the seasons of the year. As the year advanced, the shadow would cast its point in different places. And there were labels in Greek about the seasons and their winds and weather. So this monument conveys quite a complex set of messages. Greek mathematical and astronomical learning, the obelisk points towards Augustus’ capture of Egypt in 30 BC, the emperor is set up as an agent of the heavens and a reformer of the calendar, and there’s a wow factor.

This is a clever, fancy, novel piece of monumental building that creates something new and exciting in this parkland up in the northern Campus Martius. So, like the temples, it’s a marker of the emperor’s role as mediator between heaven and earth but in a very different way.