On their decades-long march across Europe, the Romans got used to eating lunch on the move. Most of their contributions to modern day civilisation are well documented, but along the way they also liked to indulge in the simple pleasures of the picnic.

Sitting by the banks of the River Usk, in the beautifully preserved Caerleon amphitheatre, it’s easy to imagine an off-duty legionary in this very spot, perhaps sharing some red wine and snacks with a local girl. To the recently defeated Silurian tribes of South East Wales, brought up on a diet of meat and (if they were lucky) two veg, Roman fare must have seemed impossibly exotic. Dates and dried figs, brought here by trading ships from the Mediterranean, would have been unloaded on the banks of the river Usk.

They also introduced smoked cheese and strange looking plants such as the cucumber, perfect for picnics, but perhaps a little unusual for Silurian palates.

On the European mainland, more established Roman towns in Gaul would have been surrounded by snack bars called thermopolii where he could have bought the girl hot sausages, nuts, honey cake and wine. Communication between them might have been a problem - he spoke only Latin and she didn’t understand it - but the number of SilurianRoman households established in the area around 100 AD suggests that spots such as this would have seen their share of courting.

The amphitheatre where this imaginary young couple met was built just outside the walls of the fortress at Isca. Once known as the “city of legions”, Isca is the present day town of Caerleon, near Newport in Gwent, and is the most important Roman site in Wales. For 300 years, it was mostly used to train the 5,500 soldiers of the Second Augustan Legion stationed there and was large enough to seat them all. You can pause and imagine the lines of soldiers wheeling, marching and drilling under the order of the centurions standing on steps now covered in grass. The amphitheatre might not have seen much mortal combat - gladiators’ high wages made them an expensive entertainment - but there would have been cock sparring and other spectacles to keep the locals entertained.

Today the amphitheatre is an impressive and tranquil spot. For centuries it lay undiscovered, a grass covered earthwork that was known as King Arthur’s Round Table and which some people still believe was the site of that mythical meeting place. Over the years, informal “excavations” - or straightforward plundering - took place as locals dug up stones for use in buildings, which can still be seen in many of the town’s houses. Partial excavation of the site in 1909 revealed walls so sturdy that in 1926 the decision was taken to uncover the amphitheatre by excavating nearly 30,000 tons of earth, with archaeologists confident that it could withstand exposure to the elements.

So it has, and the amphitheatre, on the outskirts of the modern day town, is still the best preserved in Britain. You can walk in through one of the original eight entrances before climbing up on to the gently sloping grassy mounds that encircle it to unfurl your rug and unpack the hamper.

But if you simply snatched a burger in Caerleon, don’t feel too bad - you are following an imperial tradition. “Fast food was invented by the Romans,” says Sally Grainger, a chef and food historian. “All the poorest people in Rome lived in blocks of flats and cooking was just too much of a fire risk on the higher floors. So eating on the street was very common and burgers and hot dogs were on offer.” Meat was high status, she says, but ordinary people got their fill through sausages, burgers and meatballs, often containing animal bits that richer folk would not touch. (Not much change there then.) Aside from snacking on the street, the Romans also enjoyed another form of al fresco dining. Carrying on a Greek tradition they would feast at their ancestral tomb on the anniversary of a death. “It was a picnic,” says Mrs Grainger. “You would have either some kind of spit-roasting mechanism or you would take pre-cooked food. And you would sit on the tomb and eat your meal.”

Wealthy Romans also picnicked in their own backyards, as shown by the remains of outdoor dining rooms in Pompeii and Ostia. In enormous gardens splashed with fountains, they would recline on couches under awnings of grapes or flowers. There slaves would serve what was basically a barbecue, using portable cooking platforms. But don’t go trying a Pompeii picnic in Isca’s amphitheatre. “No barbecues,” says Dai Price, the education officer of the Roman Legionary Museum in Caerleon. Mr Price is adept at transporting children back 2,000 years, helping them to see the past not just in the remains of Isca’s amphitheatre, baths and barracks, but also in the layout of the streets and the position of the church. He tells them that a legionary’s life wasn’t a bad one. Discounting the risk of a nasty death far from home, pay and medical care were good and even the food was reasonable. Legionaries were given basic rations of cheese, vegetables, corn and wheat. They would have to carry these on manoeuvres, which were basically picnics with weapons. “They would have brought rations with them,” says Mr Price. “They would have carried plenty of corn for bread, a flask of red wine, blankets, pickaxes, spare shoes and cooking pots. And they could have hunted for meat.”

As the legions marched across Britain, wagons of saucepans and Samian ceramics clanked along behind. Amphorae of wine and olive oil crossed the seas, as did almonds, pine cones and kernels, and pepper. Romans liked elaborate, highly flavoured food, so the Silurians would have got used to the smell of ginger, cinnamon, garlic and a strong fermented fish sauce called liquamen or garum, possibly a precursor of Worcestershire sauce.

They loved herbs and cheese. They introduced animals including pheasants, peacocks and possibly deer. Even the good old British cabbage was actually a Roman import, travelling in company with other vegetables such as onions, shallots and leeks.

But potatoes hadn’t arrived in Britain yet. So if you do opt for that burger, for authenticity’s sake, you’ll have to skip the chips.

Caerleon Tourist Information, www.caerleon.netintroindex, tel 01633 422 656, email: caerleon.tic@newport.gov.uk

AL FRESCO DINING, ROMAN STYLE

A picnic with a Roman flavour need not be complicated. Lunch, called prandium, was a simple affair of bread, fruit, cheese, with perhaps some leftovers from last night’s dinner, washed down with a weak red wine.

If you want to be more adventurous buy some peppery, herb-rich sausages. To get the idea of what Romans liked consider this recipe for Lucanian sausages by Marcus Gavius Apicius, a gourmet who wrote his cookbook “De Re Coquinaria” about the time Isca’s amphitheatre was built. Grind pepper with cumin, savory, rue, parsley, condiments, bay berries, and garum (fish sauce). Mix in minced meat, then grind it all again. Mix with plenty of fat and pine nuts, fill a casing stretched extremely thin, and hang in smoke.

If you fancy making something yourself, try this salad.

Sala Cattabia Line a mould or bowl with wholegrain bread. Add layers of grated hard cheese, pine kernels, cooked chicken meat, cucumber, chopped onion. Pour over a dressing made with red wine vinegar, diced ginger, chopped coriander, olive oil, celery seeds and honey. Cover bowl with a plate and put a heavy weight on it to press down the salad. Then pop into the fridge overnight. (The Classical Cookbook by Andrew Dalby and Sally Grainger contains a detailed version of this recipe.) Finally, Apicius’s cookbook contains this recipe for a dessert that’s easy to transport.

Dulcia Domestica (or “Housemade dessert”).

200g fresh or dried dates, 50g coarsely ground nuts or pine kernels, pinch of salt, honey, or red wine with honey (to stew).

Take the stones out of the dates and fill them with nuts or stone-pine kernels. Sprinkle a bit of salt on the filled dates and stew them in honey or honey-sweetened red wine. The dates have to be cooked on low heat until their skin starts to come off. This takes about five to 10 minutes.

Where to do it

* Hadrian’s Wall, the most famous frontier in the entire empire.

* Verulamium Park and Roman Museum in St Albans.

* Wroxeter Roman city in Shropshire is a treasure trove l For atmosphere try the Hardknott fort, in Cumbria.

* Beside the Multangular tower in the Yorkshire Museum Gardens, York.

* The Roman walls of Silchester in Hampshire

* Newport Roman villa on the Isle of Wight

* Chedworth villa, Gloucestershire, one of the largest Romano-British villas in the country.