Tunis, like all the best cities, is a mosaic. The heart is quintessential Arabic, an ancient warren infused with energetic commerce. Beyond it spreads French elegance from the colonial era, interrupted by the archaic achievements of Carthage. Further out still, the dramatic Mediterranean shore is shared by tycoons and tourists – with a sprinkling of artists thrown in for colourful measure.
The eye of most visitors is usually guided eastwards from the Medina towards the sea, but from Friday their attention should be seized by the suburbs to the west – and in particular Le Bardo, where the finest mosaic museum in the Mediterranean is about to reopen in a spectacular reincarnation.
First, why the funny name? Bardo has nothing to do with a certain French actress. The Tunisian version is a corruption of the Spanish word, prado, meaning "meadow". The trim, sedate suburbs beyond the city centre bear the hallmarks of a capital unrolling over farmland. But the villas and gardens and cafés defer to one dominant building: a 200-year-old palace sitting on ancient foundations. In the 19th century this was the official residence of the beys (rulers), but since 1888 it has hosted Le Musée National du Bardo.
Tunisia's national museum is unlike the collections you usually find in the the countries that ring the Mediterranean. As is customary, there are sculptures and images in abundance, and other artefacts that slice sections through the continuum of the nation's tangled history. But where the Bardo leads the Med is in its magnificent collection of Roman and Byzantine mosaics. The power and artistry projected through the ceramic chips are undimmed by the two millennia since consuls and merchants indulged themselves in palaces across present-day Tunisia.
For much of its life, the Bardo emulated the Prado. Like the mighty Madrid museum, it was burdened with a heavy, gloomy interior. As a result, it seemed almost begrudging in revealing its treasures to the visitor. But the reincarnation sheds more light on the collection, in every sense. The integrity of the original palace has been preserved, but a vast extension adds light and space and transforms your appreciation of the art.
When you walk from a bright Tunisian morning through the shiny new entrance, your eyes have to adjust – not due to the changing light, but because of the sheer wide-eyed magnificence of the work that greets you. Discs of colour and energy crowd together on a newly constructed wall beneath a skylight. The painstaking elevation to a vertical work of art for modern connoisseurs took many months, man hours and metres of scaffolding.
The extension has been cleverly created to wrap around the biggest mosaics, with platforms surreptitiously inserted to allow you to glimpse more closely into the ancient world. And the more you gaze, the more parallels you observe with modern life. Men hunt – in one mosaic, using a chariot fancifully hauled by a pair of tigers. They travel, though the well-armoured expeditions on land and sea suggest that these were not peaceful explorations. They indulge, with the vine a recurring symbol. And they think, slay and play – three berobed gamblers display much the same emotions as 21st-century players.
Later, they pray. Waves of Christian artists devoted their energies to Byzantine chapels, with a 6th-century baptismal font of implausible intricacy a key exhibit. Then Islam arrived, with its artistry encapsulated by the fabric in the older part of the building – such as the entrancing geometric perfection of the domed ceiling in the Virgil Room.
Professor Taher Ghalia is the man who found himself, after the Ben Ali regime was deposed in 2011, with one of the most challenging portfolios in the Arab world. He became president of the Heritage Committee, responsible for the nation's antiquities in general and the Bardo Museum in particular. He remains enthused: "You can see in the Bardo all the cultural identities... it's the flagship of the heritage of Tunisia."
Friday's reopening will provide important punctuation for the new Tunisia, an essential stage in reclaiming the tourists on whom so many families' livelihoods depend. Work continued through the temporary political turmoil, and has been finished despite the multiple urgent calls on the new government's energy and financial reserves.
Like the crucial element in a mosaic, the Bardo completes the Tunisian picture. Most visitors are likely to be on day excursions from resorts south of the capital, or time-pressed cruise passengers who merely glimpse the treasures as they race through Tunis. But such is the power of the collection that some will be tempted to return for a long weekend devoted solely to the city.
For travellers weary of the obvious Mediterranean city breaks, Tunis is a joyful discovery. Prosaically, it is barely any further (BA's morning departure from Gatwick to the city takes only 10 minutes longer than its counterpart to Naples), and the weather is usually warmer. Ted Wake, managing director of Kirker Holidays, plans to contact his "most discerning" clients as soon as the Bardo opens, to invite them to explore the city with a professional guide: "I am sure the Bardo's refurbishment will encourage more visitors".
Those visitors will discover that Tunis takes pride as the place where the Arab Spring began the toppling of dictators. A 10-minute cab ride catapults you into the hubbub of the Medina – which is less touristy than it was. After holidaymakers were airlifted out in January 2011, the commercial slack was taken up by makers of pots and pans and religious trinkets. Tourist essentials – such as T-shirts reading "Game Over" with a picture of the Tunisian uprising – are making a comeback, but the air is heavy with spices rather than suncream.
Barbed wire still protects government buildings flanking the main avenue to the docks, but one element of streetscape shines through: the name plate for Place 14 Janvier 2011, the square where the people's will prevailed. Its colours (gendarme blue on sombre green) and font may owe more to the French than to the Romans or Byzantium or Islam, but this is – after all – just one more chip in the constantly changing mosaic of Tunis.
Simon Calder paid £240 for a Heathrow-Tunis return on Tunisair (020-7734 7644; tunisair.com); also weekly flights from Manchester. BA (0844 493 0787; ba.com) flies between Gatwick and Tunis.
He paid £99 a night for B&B at Mövenpick Hotel Gammarth, Tunis (00 216 71 741 444; moevenpick.com), booked through LowCostHolidays.com.
Taxis are around 1 dinar (45p) a mile – and usually reliable. Insist the driver uses the meter.
Bardo Museum (00 216 1 513 650; bit.ly/MusBardo) 10am-5pm daily.
Tunisian National Tourist Office (020-7224 5561; cometotunisia.co.uk).