Cardiff or Nantes?

Neither city has a beach of its own. In Cardiff the brown, tidal water of the Bay is for looking at. Barry Island's funfair sands are half an hour away by train and Penarth has pebbles and a pier, but you need a car for the better beaches at Porthcawl and Gower, and the sea stays cold enough that most people only paddle.

Nantes gets you to better sand. La Baule's long, sheltered bay and the coves at Pornic are about an hour away by train, and in late summer the Atlantic is warm enough for a proper swim on calm days.

Cardiff's best eating is in the bistros of Pontcanna and Canton, along the South Asian and Middle Eastern run of City Road, and in the Victorian market with its griddled Welsh cakes, cawl and laverbread. The local ales are good, but the Bay waterfront is mostly chains.

Nantes has a real regional kitchen. Beurre blanc was invented here and is served on pike-perch or sole, oysters come in from the nearby coast, galettes show the pull of Brittany, and Muscadet grows just outside town. The set lunches in the Bouffay lanes make eating well easy in a way Cardiff does not quite manage.

Each city gives you two or three good days of sightseeing, and each is built around a castle in the centre. Cardiff's castle has Victorian Gothic rooms inside Roman and Norman walls, and the city adds the National Museum's Impressionists and the rebuilt Welsh farmhouses and miners' institute at St Fagans. Little of the city itself is older than Victorian.

Nantes has more of its past in the streets. There is the ducal château with its frank account of the slave trade, a Gothic cathedral, the leaning merchant houses of the Ile Feydeau and the Jules Verne museum. Cardiff is the place for Welsh folk and industrial heritage, Nantes for an old townscape to wander.

Both are student cities with a similar amount going on after dark, but the mood differs. Cardiff is about weekends, with big groups on St Mary Street, crowds in red on rugby days and Womanby Street's small alternative bars as the more interesting corner.

Nantes is more about terraces and wine bars. Evenings start in the medieval Bouffay lanes and move later to the old banana warehouses on the Ile de Nantes, where the clubs stay open until the early hours. Both are quiet midweek.

Cardiff has real hills within reach. Pen y Fan and the open ridges of the Bannau Brycheiniog are about an hour's drive away, the Taff Trail climbs from Bute Park up the valley, and the coast path follows the cliffs around Penarth and the Vale of Glamorgan.

Nantes is flatter and gentler. You can take a boat up the Erdre, cycle the Loire à Vélo route through the vineyards, watch birds from a punt in the Brière marshes or walk the cliffs of the Côte Sauvage. It suits cyclists and walkers who like level ground, but there is no summit to aim for.

Both make excellent bases, but the outings are different. From Cardiff the themes are castles and industry: Caerphilly is twenty minutes by train, Castell Coch stands in the woods, and you can pair Tintern Abbey with Chepstow or go down the Big Pit mine at Blaenavon. Bath and Bristol are just across the Severn.

From Nantes the trips are about old towns, wine and the coast. There is walled Guérande above its salt marshes, Angers with the Apocalypse Tapestry, Saumur and the Loire châteaux, Clisson among the Muscadet estates and Vannes on the Gulf of Morbihan.

Cardiff is compact and flat, and most of what families do there is free. Children get hands-on science at Techniquest, farm animals at St Fagans and rowing boats on the lake in Roath Park, but there is no zoo or theme park.

Nantes has the bigger draws. Riding the giant mechanical elephant or the sea-creature carousel at the Machines de l'Ile is hard to beat, and the safari park at Port-Saint-Père and Puy du Fou are both within a drive. Its calmer, warmer beaches also make summer days by the sea easier.

You can walk both small, flat centres. Cardiff has no metro or tram, so getting to the Bay means a half-hour walk, a shuttle train, a bus or a water taxi. Local trains take you to Penarth, Barry and the valleys.

Nantes is simpler. Three tram lines and a busway are easy to learn on the first day, small river shuttles cross the Loire and the riverside paths are easy to cycle. Paris is about two hours away by fast train. In both cities you only need a car for the countryside.

Arcades are the highlight in both cities. Cardiff has a whole network of glass-roofed Victorian and Edwardian ones, lined with independent shops selling records, books and vintage clothing. For something to take home, look for a lovespoon, slate or a Welsh woollen blanket.

Nantes has a single grand arcade, the three-level Passage Pommeraye, with better boutiques around Graslin and independent shops near Bouffay and Decré. Its souvenirs are mostly edible: salted-butter biscuits, berlingot sweets, Guérande salt and Muscadet. Either city takes about an afternoon.

A trip costs about the same in each, but you save in different places. In Cardiff, the free national museums, including St Fagans, and short, cheap train trips to the castles and coast make up for typical British restaurant prices. Hotel rates jump when the stadium hosts a rugby international or a big concert.

In Nantes, hotels are easy to find and the set lunch menus are the bargain. Dinners and drinks cost what they do anywhere in France, and the coast gets pricier in high summer.

Both have more going on stage than you would expect for their size. Cardiff relies on national institutions: Welsh National Opera at the Wales Millennium Centre, the BBC National Orchestra of Wales, big concerts at the stadium and rising bands in the small rooms of Womanby Street.

Nantes has more festivals and experiment. La Folle Journée packs hundreds of short classical concerts into a few days each winter, the opera plays at the Théâtre Graslin, the Lieu Unique stages contemporary work, and giant street-theatre puppets fill public spaces.

The real difference is the sea cure. Nantes has France's thalassotherapy tradition within reach, while Cardiff has only hotel spas. In Cardiff, relaxing means a day spa, the leisure pool at one of the Bay hotels, a slow morning in a Pontcanna café or a stroll along the Taff.

From Nantes, the long-established seawater centres at La Baule and Pornic, about an hour away, make a restful day out. In town, the Jardin des Plantes and the banks of the Erdre are good for a slow afternoon.