Lille or Marseille?

Beaches are no reason to choose Lille. The nearest sand is at Dunkirk, and the North Sea there stays cold even in August. The Opal Coast dunes are better for a windy walk or sand yachting than for a swim.

Marseille is a real seaside city. You can swim from the Prado beaches and the little coves along the Corniche, or spend half a day reaching the turquoise water of the Calanques on foot or by boat. Two drawbacks remain: the mistral can chill the water overnight, and the city beaches sometimes close after heavy rain.

Lille's cooking is hearty northern food from the old Flemish tradition, served in wood-panelled estaminets. Expect beer-braised carbonnade, potjevleesch, the welsh and plenty of pungent Maroilles cheese, with Belgian and northern ales rather than wine. It is satisfying, but the range beyond regional dishes is narrow.

Marseille gives a food lover more to explore. It has the ceremony of a proper bouillabaisse by a Corniche harbour, a high-end tier built around fish, and everyday food from all over the Mediterranean, with panisses and pizza and the spice shops and grocers of Noailles. Its weak spot is the tired set menus around the Vieux-Port.

The two are well matched, but the experiences are different. In Lille the treasures are gathered close together: the Palais des Beaux-Arts with its Flemish masters, a preserved brick-and-stone baroque old town, the UNESCO-listed belfry, and La Piscine in Roubaix a metro ride away. Two or three days covers them all.

Marseille's history goes back further, to its Greek founding, but it is scattered through a working city. You climb to Notre-Dame de la Garde, cross the footbridges from Fort Saint-Jean to the MuCEM, wander the stepped lanes of Le Panier and take a boat to the Château d'If. It is less about paintings and more about the port and its long past.

In Lille the students set the tone, and in Marseille the weather does. Lille's busiest nights are the cheap, loud Thursdays on Rue Masséna and Rue Solférino. Vieux-Lille has calmer beer cafés and cocktail bars in old brick cellars, and for serious clubbing people have traditionally crossed into Belgium.

Marseille goes out on terraces and in the street, around Cours Julien and La Plaine, with pastis on the Vieux-Port quays, electronic nights in old warehouses and summer parties by the sea. It is at its best on warm nights and thins out in winter. Some central streets feel edgy late at night, so a taxi home is sensible.

Lille's outdoors is gentle: the green loop of the Citadel park and Bois de Boulogne, level towpath cycling along the Deûle, and short walks on the low Monts de Flandre. The chalk cliffs of Cap Blanc-Nez are the nearest real scenery, and they take a long day.

Marseille is in another league. The white limestone ridges and deep blue inlets of the Calanques national park begin in its southern suburbs, and Sainte-Victoire and the Sainte-Baume forest are within an hour. Go in spring or autumn, because summer heat and fire risk can close the massifs.

Both make excellent bases, but the trips are different in kind. From Lille they cross borders by fast train: Brussels is about half an hour away, Ghent and Bruges an hour or a little more, and Paris around an hour by TGV. On the French side, the arcaded squares of Arras, the Gothic cathedral at Amiens and the Louvre-Lens make easy days out by rail. The exception is the First World War battlefields and memorials around Ypres, Vimy and the Somme, which need a car or a tour.

From Marseille the trips go deeper into Provence instead of abroad. Aix, Arles, Avignon and the little harbour of Cassis are simple by train or bus. Much of the region's best is countryside, though, and the Luberon hill villages, Les Baux and the Bandol wine estates are far easier with a car.

Neither city is built for children, but each suits a different kind of family day. Lille has the small zoo and playgrounds in the Citadel park, a hands-on science centre by metro, and Pairi Daiza and the Nausicaá aquarium within reach, so a rainy day is easy to fill. The cobbles of Vieux-Lille are the main nuisance.

Marseille is a summer outdoor choice: the Prado beaches, the lake and lawns of Parc Borély, and boat trips to the islands. It has no zoo or aquarium, and with steep streets, traffic and heat, families with a buggy are best off staying near the southern beaches.

Lille is much the easier city to move about in. The centre is flat and compact enough to walk everywhere, the two main stations stand a short stroll from the old town, and the automated VAL metro and the tram cover the suburbs.

The centre of Marseille is walkable but steep, and the metro and trams mostly serve the centre and the north. The beaches and Calanques trailheads depend on buses that crawl through traffic, although the summer ferries across the bay are a pleasant way round it. A car is a burden in town and useful only for the villages beyond.

Lille is the better place to shop. The narrow streets of Vieux-Lille hold independent fashion, design shops and delicatessens, and Rue Neuve and Euralille cover the chains. Each September the Braderie turns the whole city into a vast flea market.

Marseille's shopping is about local goods rather than fashion: green cubes of Marseille soap, painted santon figures from Le Panier, and the fabrics and teas of Noailles. Anyone after boutiques or designer names will run out of streets quickly.

Costs are similar in both, comfortable rather than cheap. The difference lies in when prices rise. In Lille, rooms fill up and cost more during the Braderie and the big trade fairs. In Marseille the jump comes in July and August near the Vieux-Port and the beaches. Marseille also makes a tight budget easier, with cheap street food, low museum entry and free walking in the Calanques.

Lille's stages lean classical, and Marseille's lean popular and Mediterranean. In Lille the grand Opéra on the Place du Théâtre, the Orchestre National's symphonic season and the Théâtre du Nord form the core, with contemporary dance in Roubaix and Tourcoing.

Marseille has its own art deco Opéra and the national theatre of La Criée, in the old fish market. Its character comes from elsewhere, though: the converted tobacco factory of the Friche la Belle de Mai, a strong place in French hip-hop and world music, and festivals such as the Fiesta des Suds.

Neither city is a place to come for rest. Lille offers hotel spas, tea rooms and café terraces in Vieux-Lille, and its one real thermal bath is a short train ride away at Saint-Amand-les-Eaux.

Marseille is noisy and intense in the centre, but it gives a slow day more to work with: a long lunch by a little harbour on the Corniche, a morning swim, a local hammam. Many visitors who want real calm stay in Cassis and come into the city by day.