Water is the key to the seven civilisations that have left their mark on the history and architecture of Tunisia.

Carthage was founded in the 8th century BC by Phoenician sea-traders from the Levant. As a maritime people they chose their site on an easily defended peninsula. A lagoon, today called the Lake of Tunis, offered safe anchorage and rich fishing.

Carthage flourished, built a great trading empire, and became the main rival of Rome. The centre of Phoenician power shifted from Tyre to the new naval base of Carthage. The confrontation with Rome led to three Punic Wars.

The Roman statesman Cato was greatly alarmed at the city's wealth and undiminished power, and campaigned to have Carthage eliminated. Whatever the subject under discussion, he ended every speech with the words: "Carthage must be destroyed."

In 146 BC the Romans duly conquered Carthage, and the great mercantile city was sacked, rased to the ground and the soil ploughed with salt. All that has survived today are a few Punic drains, a cemetery and an excavated housing development.

But soon the Romans were back, sent by Julius Caesar to rebuild the city bigger and better. However, Carthage had a very poor spring water supply. The excavation of Punic housing on the Byrsa Hill has revealed that every building had its own cistern for rain water collection. These were fitted with a manhole so that householders could go down periodically and clean them out.

But that wasn't good enough for the Romans, who liked to have a proper bath, frequently. They couldn't meet their increasing domestic needs from rainfall alone. Faced with supplying a city of over 700,000 inhabitants, they built a magnificent aqueduct that carried 6,000,000 gallons of water daily into Carthage from hills 44 miles away. The volume was also enough to feed the beachside Baths of Antoninus, which covered a floor space of nine acres. It was a vast capital investment even by today's civil engineering standards.

The water came from Zaghouan, which is due south of Tunis and backed by mountains with fever-chart peaks rising to 4,000 feet. Fed by abundant winter rains, the lower slopes gush with springs of sparkling water. The main source is marked by the 2nd-century Nympheon (Temple of Waters), a theatrical monument set against the towering mountain backdrop.

On two wings of the Temple, colonnades held niches for a dozen statues representing the months of the year. The huge semi-circular marble fountain ends with a gigantic basin where the water was collected for onward transmission.

The present-day spa town of Zaghouan is a prosperous green oasis. Nearby, a few ground-level sections of Roman aqueduct are visible. Wherever hills stood in the way, a conduit was carved through. Nearer Tunis, the great arches of the aqueduct stride majestically across valleys. Today, Zaghouan still supplies Tunis, along a pipeline which follows exactly the same alignment.

The wide-spreading plain watered by the Zaghouan mountain became part of the granary of Rome. In contrast to the maritime Punic traders, the Romans were colonizers. Using slave labour, landowners established rich estates that grew corn, vines, olives and fruit, which provided Rome with the essentials for "bread and circuses".

The remains of luxury Roman villas have supplied the Bardo Museum of Tunis with the world's finest collection of mosaics. They give a vivid impression of the Roman lifestyle: hunting, feasting and drinking, sport and entertainment.

In 439 AD the Vandals swept in and Carthage was wrecked again. The Vandals had a talent for destruction. They castrated Roman statues and knocked off their noses, to symbolize triumph over their impotent enemies. The Vandals enjoyed 100 years of anarchy, which ended when the Byzantines drove them out in 535.

Next came Arab rule. The Arabs preferred to let ancient buildings fall apart, and then cart off any bits that might come in handy. Over the centuries, the stone quarry that was Carthage was fully exploited, so that only basic and widely-scattered outlines remain.

Building materials were recycled and shipped out for any project-such as the cathedrals of Genoa and Pisa-that needed ready-made columns and dressed stone. Today even the poorest tenement houses in Tunis possess marble stairways, whilst carved inscriptions to Jupiter make excellent doorsteps.

Carthage factfile

The coastal resorts of Hammamet and Nabeul are best for a wide choice of accommodation. Trains and buses serve Tunis via Bir bou Rekba. On a Roman circuit, guided tour coaches feature Zaghouan and the remains at Thuburbo Majus and Dougga.

Operators also feature a one-day trip to Tunis-visiting the souks and the superb Bardo Museum-with a quick look at Carthage.

Go-it-alone travellers can use shoe-leather and the commuter rail service which clatters out from Tunis every 20 minutes. Get out at Carthage Salammbo station for the Tophet and the Punic Ports; Carthage Dermech for the Museum and Punic Housing on Byrsa Hill; Carthage Hannibal for the Theatre and the Antonine Baths.

Published in Travel Africa Edition Eleven: Spring 2000 Text is subject to Worldwide Copyright (c)