Tunis, Tunisia — At the time of Christ Tunisia was to Rome what India once was to Britain - the most densely populated and coveted of overseas possessions. The fields of Africam Nova constituted the breadbasket of Rome during an age when Rome ruled the world. In Italy, ruins evoke ''the Republic.'' But in Tunisia, the site of a colosseum, as large as the one in Rome, standing in the middle of a remote mud-brick village evokes ''the Empire.''
The Roman ruins of Tunisia are the most unspoiled and dramatically situated of all ancient sites around the Mediterranean and most can be seen as one-day bus or car excursions from the capital city of Tunis.
It is their ambiance which makes archaeological sites in Tunisia special; there are no tacky souvenir shops or noisy highways nearby. Today - with many of the sites not even properly excavated - they exude the same quietude that the French novelist Andre Gide must have experienced when he visited them half a century ago. Sheep are at home among the columns and fallen lintels, and wildflowers poke their noses through the cracks of mosaic tiles.
There are over 50 archaeological sites in Tunisia; and the museums of Tunis, Sousse, and Sfax account for the largest collection of Roman mosaics in the world.
Roman rule in Tunisia officially began in 146 BC when Carthage was razed at the end of the third Punic War (Punic, referring to the Phoenician dialect spoken by the Carthaginians). A new Roman city was erected on the ashes of the old one: the capital of Africa Novam (New Africa), a Roman province whose borders corresponded roughly to those of present-day Tunisia.
The ruins of Roman Carthage comprise over a dozen sites only one-half hour from downtown Tunis by electric train (the station is at the Place D'Afrique, at the end of Avenue Habib Bourguiba). The place setting is truly magical, and I spent an entire day there. It was well-described by Gustave Flaubert in his historical novel about ancient Carthage, ''Salammbo.'' He wrote ''. . .a grove of sycamores stretched away toward dark green thickets where pomegranates glowed; grape-laden vines climbed into the bows of pines; . . . and the cypress avenue which cut the ground in two was like an aisle of green obelisks.''
From where I stood on a cliffside fecund with marigolds, poppies, and an occasional cactus, the mud-brick forms of the 1st-century baths of Antonius stood out like monoliths as the breakers from the Gulf of Tunis bashed the columns of an adjacent Roman gymnasium, flooding its marble floor by the beach.
On the other side of the gulf I could discern the dark-green silhouette of Djebel Bou Kornine (Two-Horned Mountain), which the Carthaginians believed to be the lair of their god, Ba'al Hammon.
The finest view of the entire area is afforded from the nearby Church of St. Louis, erected in 1884 in Moorish-Byzantine style and named after the French king who led a crusade to the Holy Land, but whose army never got beyond Carthage on account of a plague.
Close to the church is the Carthage Museum, a quaint two-story structure with a garden evocative of Chatsworth in ''Great Expectations.'' But instead of ''worthless bric-a-brac'' here are archaeological treasures, each of which tells a poignant tale. There are tiny cisterns holding the remains of infants sacrificed to Ba'al Hammon, and a sarcophagus with a hole in its top, made perhaps by a Roman in the process of stealing jewels. A statue of a Roman goddess - the head lopped off by an invading Vandal in the 6th century - testified to the repeated destructions that Carthage had undergone.
Other Roman sites at Carthage include an odeum, antiquarium, and an amphitheater where St. Perpetua and St. Felicita are said to have been martyred. But what of the great Punic-era city whose influence once extended into Spain and southern France under the stewardship of Hamilcar and his son, Hannibal? Little remains with the exception of the sanctuary of Tanit (the consort of Ba'al). The various levels of ruins there date from the 8th through the 2nd century before Christ.
Those unwilling to part from the spell of Carthage can stay overnight at the Reine Didon next to the museum. The price for a double room is about $35. The view, like the one from the church, is magnificent.
Roman rule in Tunisia was initiated at Carthage, but its apex in terms of architectural splendor was reached at Dougga; the largest, best-preserved and most spectacularly situated of all Tunisian archaeological sites. Without a car, it is a two-hour bus journey from Tunis to Teboursouk, and then a two-mile hike. But it is well worth it. When I arrived, the ruins were tinted a brilliant ochre from the late afternoon sunlight and shepherds were taking their sheep out for grazing on the sienna-hued hills.
Dougga (called ''Thugga'' in ancient times) was a residence of Massinissa, a Numidian king and Roman ally. The remains of the Roman city date from the 2nd and 3rd centuries and rise in tiers on the slopes of a mountain, striped with row upon row of olive trees. Not only are there baths, several temples and forums, and a theater, but streets and houses in good states of preservation. With the obvious exception of Pompeii, perhaps no other Roman site anywhere recaptures the mood of a now-deserted city as well as Dougga.
Among other worthwhile Roman sites in Tunisia are:
Utica. Less than an hour north of Tunis is the first Phoenician settlement in Tunisia, but the acre-sized remains date mostly from the Roman-era city of Cato. A few minutes away from the actual site is a small museum and an adjacent mosaic of Neptune in excellent condition.
Thurburbo Majus. Remnants of a forum, thermal baths, and private dwellings paved with mosaics make up this city founded by Roman Army veterans in 27 BC. The ride south from Tunis takes one hour, and passes the remains of a Roman aqueduct along the way.
El Djem. The colosseum here is as large and better-preserved than the one in Rome; and standing as it does in the middle of a humble village in the desert, it is far more striking. Four hours south of Tunis by train, El Djem is best visited as a half-day excursion from either Sousse or Sfax.
Maktar. The remnants of one of the loveliest towns in Africa Novam lies on a high plateau in the center of Tunisia, three hours southwest of Tunis. A completely preserved forum paving, thermal baths, an amphitheater, and a triumphal arch from the time of Trajan are the highlights. Be prepared for cool weather and strong winds.
Sbeitla. Like Maktar, Sbeitla sits on a windy steppe, and it feels almost as though time itself is racing through the ancient columns. A monumental gateway and three temples survive from a Roman town whose past is still murky, since the site has yet to be excavated in depth. Four hours southwest of Tunis, Sbeitla - like El Djem - is best seen as an excursion from either Sousse or Sfax.
Tunis, Sousse, and Sfax will be your bases for exploring Tunisia's Roman inheritance. The archaeological museums in all three cities close between 12 and 2 in the afternoon. The Bardo in Tunis houses one of the world's largest collections of antique art, and should not be missed. And the medinasm (native bazaar quarters) of Tunis and Sousse are among the loveliest in the entire orient.
All three cities contain several hotels in all price categories. In Tunis, the Maison Doree is my favorite; a stately old establishment with painted-tile walls, French windows, and one of the city's best restaurants, and costing $25 a night for a double. Dinner there for two will run under $15.
The best time of year for a visit is the spring, when the wildflowers are in bloom. But fall and summer are also comfortable. Winters can be very rainy and extremely cold on the plateaus where many of the ancient ruins are situated. So if you go then, bring warm clothes and a raincoat.
For guidebooks, Fodor's North Africa includes Tunisia along with Algeria and Morocco. It provides maps and thorough descriptions of several major Tunisian sites. Also, Tunisia publishes excellent brochures on its own past. Pick them up at any Tunisian government tourist office. The most detailed account of Rome's conquest of Tunisia is Livy's ''The War With Hannibal.''
Adjacent Algeria is also dotted with fine Roman-era sites, whose situations are as untouched and scenically spectacular as those in Tunisia. But sadly, hotels and restaurants in Algeria run about 25 percent higher in price, while service and cleanliness do not match Tunisia's high standards. In addition, United States citizens must obtain visas prior to visiting Algeria.
But those real archaeology enthusiasts who go will find Algerians themselves thoroughly warm and hospitable. The most worthwhile sites in Algeria are Constantine, El Khroub, and Hippo Regius (Annaba) near the Tunisian border in the east; Timgad in the Aures Mountains; and Tipasa, a 90-minutes drive west from Algiers, along one of the most unspoiled sections of the Mediterranean coastline.