Three hours exploring the dark tunnels inside a tomb, inside a castle on the banks of Rome’s River Tiber has given Professor Greg Woolf , director of the Institute of Classical studies, a whole new perspective on the Castel Sant’Angelo – the castle of the holy angel.

There really is a spectacular angel on the roof. The statue and the name commemorate the moment Archangel Michael appeared with a flaming sword to give courage in the darkest days of Rome’s Dark Ages in 590 when the city was nearly deserted, already falling into ruins, and ravaged by plague.

But the castle itself, reinforced, extended, given buttresses and canons in later periods is wrapped around the vast tomb of the emperor Hadrian, the most restless of Rome’s rulers who left his mark on Egypt and Athens and Africa and even on our island, but whose remains were buried in the capital.

My guide around the innards of the tomb Paulo Vitti, a prizewinning architect who specialises in the reconstruction and understanding of ancient buildings, has spent years working out what the tomb looked like before it was castellated, how it was built and what the rationale for its design was. One part of that rationale is a set of internal passages that deliberately disorientated visitors so that they approach first the emperor’s tomb and eventually, his rooftop temple. Most Roman emperors became gods on their death. Enter the darkness, climb, wind, turn sharp corners and suddenly emerge into the light in a moment of revelation.

Today, being guided by Paulo through Castel Sant’Angelo leads to a different kind of revelation. Following his detective work step by step and sometimes stone by stone leads to a Roman monument that turns out to have survived almost intact inside the later fortress.

I first heard about Paulo’s work when he came to speak at the Institute of Classical Studies (ICS) earlier this spring. His lecture, which can be watched online, was one of a series run jointly by the ICS and the British School at Rome (BSR), a research academy that since 1901 has been home to a shifting population of historians and artists, classicists and architects, anyone in fact who has a reason to carry out research in Italy. BSR has a magnificent library, hosts some major archaeological projects (including the recovery of the spectacular port of Rome built by Hadrian’s predecessor Trajan), runs a packed programme of workshops and conferences and also courses for students and researchers.

Like the other BASIS Institutes (and like the School of Advanced Study) it provides vital infrastructure for research projects of all kinds. And perhaps more important of all, acts to foster international networks of scholars. UK classicists lecture in Rome every year too, and from the connections they make come student exchanges, new scientific collaborations and invitations like the one that led me into the Mausoleum of Hadrian.

Paulo Vitti is part Greek, part Italian and part of his family is from Istanbul. He has worked on Cyprus and in the Peloponnese as well as southern Italy and in Rome, where he not only runs his architectural practice but also lectures at La Sapienza University. Hearing him address an audience in Bloomsbury – and through the ICS website potentially everywhere else as well – was not just a huge privilege. It was also a fantastic illustration of how important these connections are.

Hadrian joined up his empire by travelling back and forth all over it with a train of soldiers and slaves, courtiers and other hangers on. Making and sustaining connections is a bit easier these days, but just as vital.

Professor Greg Woolf is a cultural historian of the Roman Empire and surrounding regions. Much of his work uses social theory to connect archaeological and historical information about antiquity. He has written on the cultural dimension of the expansion of the empire, Roman imperialism, economy and intellectual culture and also on Iron Age hill forts, ancient ethnography and the assassination of Julius Caesar. Professor Woolf has coedited collections on ancient literacy, ancient libraries, encyclopaedic culture in pre-modern periods, the city of Rome, women in Roman cities and on ancient senses of the self.  His latest monograph is Rome. An Empire’s Story.