I PROBABLY had no choice about becoming a historian: by age seven I was helping out at Roman digs near my home in Godmanchester, and childhood holidays invariably involved ticking off stately homes and cathedrals. If we did go to the beach, we’d end up building very elaborate models of Caernarfon Castle. That’s not a joke: I’ve really done that. Well, you can’t help noticing how the moats and barbicans were made, can you? Recently, I moved to north Norfolk, and the beaches at Holkham and Hunstanton must have the greatest castle-building in England: miles and miles of lovely hard sand.

That set the tone: I now have this desperate disease where I’m incapable of having a normal holiday. I went to Kenya to see big game, but then somebody in a bar mentioned all the glittering coral palaces that fringe the Swahili coast. Forget elephants, I was off heritage-hunting in the Land Rover. And whereas most people go to Provence to sit outside their villa with Harold Robbins, I got a big, fat, air-conditioned Mercedes and a huge, fat book called The Roman Remains of Southern France and went looking for ancient wineries and amphitheatres around Avignon and Nîmes.

I really recommend that: there is an enormous Roman grain mill in a remote field at Barbegal, near Arles, which is one of the best three ruins I’ve ever seen. The thrill of discovery gets me every time — there I was, in baking sun, with the cicadas going and thorns ripping at my shorts, and I just wanted to sit there all afternoon. It sounds corny but I really felt I could hear the heartbeat of history.

Mass tourism is horrible. I hate arriving somewhere to find a horde of barbarians who’ve had that operation to weld a camera to their eyelids: they don’t really see things, they just photograph them and get back on the coach. Luckily, I don’t mind pulling rank to get amazing places to myself.

In Sweden, recently, I got a private tour of Drottningholm, a wonderful baroque palace that once housed the court theatre. It has the original piece of 18th-century stage machinery called a chariot, designed so actors could descend to the stage like a deity, festooned in cut-out clouds. Most people just get to look at it; I asked for a ride. So there I was, playing god, and I suddenly realised the ropes were the original 18th-century ones; they could have snapped at any minute.

As a student I went Inter-Railing, roughing it on the trains down from Venice through Czechoslovakia to Athens — a killer journey, sleeping in the corridor of the train and waking up to find a chicken had laid three eggs in your trouser pocket. That’s also when I first made it to Rome, the city I love most of all. I like the fact that Roman life still has rich indigenous roots — like at my favourite trattoria, Da Giggetto. It is right next to the Theatre of Marcellus, with Roman columns practically to the doorway, but hardly any tourists find it — it serves Roman food to Romans. They do the most amazing thing with courgette flowers, stuffed with mozzarella and anchovies, and fried — a dish they may well have been eating in Rome since Caesar’s time.

Wherever I go, I try to mix with the locals, assimilate myself. That can backfire, of course. My car got broken into in Tunisia, and the policeman was so chatty, he ended up inviting us to supper at his home. What a nice idea, I thought: but we arrived to find a really grim police barracks, where he was cooking up vile-looking goat stew over a Bunsen burner on the floor. My girlfriend was a doctor, and I could see she wasn’t going to eat this stuff, but I felt I had no choice. She knew I was going to be poisoned; I knew I was going to be poisoned; even the policeman knew, probably — and sure enough, I spent the rest of the trip delirious in bed with a temperature of 103 and my girlfriend shoving Valium suppositories up my bottom.

That serves me right for a piece of typical English folly. I’d rather die — almost literally — than offend somebody by not eating their food.