A single gleam of light down a side-street to my right marked what I knew to be the guard-post of a cohort of the Vigiles. There were no other signs of life.

We crossed the Tiber on the Pons Aurelia. In the darkness below I could hear the river at full surge. Its rushing water had an unpleasant energy. Upstream it had almost certainly overflowed its banks on to all the low ground around the foot of the Capitol, yet again turning the Campus Martius-which could be spongy at the best of times-into an unhealthy lake. Yet again turgid mud the colour and texture of sewage would be oozing into the basements of the expensive mansions whose middle-class owners jostled for the best waterfront views.

My own father was one of them. At least thinking of him having to bale filthy floodwater out of his entrance hall cheered me up.

A huge gust of wind stopped my horse dead in its tracks as we tried to turn into the Cattle Market Forum. Above, both the Citadel and Palatine Hill were invisible. The lamplit Palaces of the Caesars were drowned out of sight too, but I was now on familiar ground. I urged my horse past the Circus Maximus, the Temples of Ceres and Luna, the arches, fountains, baths and covered markets that were the glory of Rome. They could wait; all I wanted was my own bed. Rain cascaded down a statue of some ancient consul, using the bronze folds of his toga as gullies. Sheets of water swept off pantiled roofs whose gutters were quite unable to cope with this volume. Cataracts tumbled from porticoes. My horse struggled to press under the sheltered walkways against the shopfronts, while I pulled his head round to keep him on the road.