Strolling around the Estanove district, just south-west of Montpellier centre, it’s hard not to feel excited by how this Mediterranean city is transforming for the 21st century. Here, on a brownfield former military site next to leafy Parc Montcalm, the city is building one of several “eco” districts – this one will link its new Cité Créative (a cluster of schools devoted to culture and the creative industries, including animation and games art) with the park.

That will be a while away, but there are already many reasons to visit this youthful and energetic city, whose reinvention is in full swing. (It’s one of the oldest university towns in France, and according to the tourist board one inhabitant in five is a student.) Le Halle Tropisme, a former machine hall built in 1913, has in recent years been transformed into a huge creative village for live music, clubbing, festivals, flea markets and games of pétanque, with plentiful street food and natural wine and craft beer stalls.

Parc Montcalm itself is also a lively community space hosting family picnic days, concerts and more. It all feels very Berlin on the Med, somewhere you’d love to live. (I can’t be the only one feverishly Googling “immobilier Montpellier” after spending some time here.)

“Right now there’s this youthful, entrepreneurial spirit in the city,” says Fiona Joyce, an English teacher in the Cité Créative who has lived in the area for 20 years and is showing me around. “There’s a feeling of change and creativity – you stumble across music and dance events everywhere, and pop-up shops and new restaurants. There’s also forward-thinking going on at a higher level, with more green spaces, tramlines and bike lanes.”

Late summer and autumn is my favourite time in this city, when the fierce heat has abated but it’s still warm enough to hang out by the sea. Montpellier is about six miles from the coast, and the lovely golden beaches at Palavas-les-Flots and Carnon can be reached from the city centre by bike paths or tram no 3 (about half an hour plus a half-hour stroll).

And the trams are indeed a big deal here. Not only was Montpellier the first French city to make all its public transport free to residents last December, it is also expanding its tram network. As well as being easy to jump on and off, the trams are very chic. The fabulous octopus and starfish designs on lines 3 and 4 are by fashion designer Christian Lacroix, who was born in nearby Arles and studied in Montpellier. There are also 145 miles (235km) of cycle paths through the city. (Try them with Vélomagg, a cheap self-service city bike scheme.)

Having been one of the first European cities to both reintroduce trams (in 2000; they had been discontinued in 1949) and pedestrianise its centre, Montpellier has now also committed to mass tree planting – 50,000 specimens by 2026 – as part of a serious greening strategy spearheaded by Socialist mayor Michaël Delafosse.

Its waste management systems are state-of-the art and its rubbish collection is frequent too (not very sexy, but its unreasonably clean streets are a pleasure to stroll around).

Indeed, recycling – of household waste as well as entire districts – is a theme that runs throughout the city. In parts of Montpellier, especially the central Saint-Roch district, with its mix of ancient architecture and modern street art, every other shop seems to be a vintage clothing or homewares store. One of my favourites, Mireille Café Moderne, is an all-in-one charity shop, sewing corner, vegetarian cafe and comedy venue. A few steps away, the Tardis-like Pomme de Reinette et Pomme d’Api games shop, named for a French nursery rhyme, is worth a browse for everything from antiques and retro toys to vintage tarot decks.

East of the centre, the River Lez is a popular green escape used by cyclists, walkers and canoeists. A tram also runs to the riverside Marché du Lez, a group of old agricultural buildings now home to street art, flea markets, boutiques, startups and co-working spaces, as well as food trucks, bars and restaurants. Toi Toit Mon Toit has roof terrace views and occasional concerts and film screenings.

Montpellier comes across as multicultural and community-focused, and with good reason. Thirty years ago, under another visionary mayor, George Frêche, the city positioned itself as a “laboratory” for French urbanism – and has been both learning lessons and paving the way for other cities ever since. Among its achievements are investment in social and affordable housing as key to social inclusion, plus the multicultural festivals and concerts at Le Halle Tropisme and elsewhere in the city.

Not that this is anything new: in the 12th century, as Montpellier was rising to prominence as a trading centre, especially for spice, it became known for its diverse culture and tolerance. The city’s medieval heart, L’Écusson (named for its shield-like shape), is still lovely to simply wander around, with main sights including Place de la Comédie, the gothic Saint-Pierre cathedral and the Fabre Fine Art Museum.

Nowhere is this tolerant vibe more in evidence than in the villagey but gritty Figuerolles district, between the centre and Estanove, where I enjoy a Sunday lunch of merguez sausage and couscous at Le 22, a Moroccan restaurant partly staffed by Georgians on rue de la Palissade.

That evening, I get a takeaway from an Afghan venue (Au Petit Kaboul on rue de la Merci), before singing multilingual karaoke into the early hours with a cheerful crowd of locals in Délirium Café on Place Roger Salengro. It all feels very welcoming.

Inland, in the wider Hérault region, things may not be so harmonious: in the recent elections many villagers voted for Marine Le Pen’s far-right National Rally party. But there are plenty of good reasons to make a jaunt out of the city, especially the river swimming, which makes a great alternative to the beach.

A bus runs from the centre of town to Pont du Diable (Devil’s Bridge – about 40 minutes) near the gorgeous village of Saint-Guilhem-le-Désert. We join locals leaping from high rocks into the cool green water of the Hérault River and then lie lizard-like on the beach to dry off.

One day, we also tackle the river by canoe. Several companies, including Canoë Rapido, hire them out and will pick you up from various spots downriver. On our six-mile paddle we stop at whim to swim, jump off rocks, drink at riverside bars and eat a picnic of food from a local market. It was the perfect lo-fi day out before diving back into Montpellier’s glorious urban fray.

Where to stay
Hotel du Palais (doubles from €125, room-only) is a charming family-run hotel with a classic French feel and a tea room. Jost Hotel Montpellier (doubles from about €90) is a newish lifestyle hotel with rooms, apartments and dorms, a co-working space, a rooftop pool and karaoke.

• Eurostar from London to Montpellier via Paris or Lille (second leg by SNCF train) takes about seven hours, from £127 single. For local transport, visit herault-transport.fr. More information at montpellier-france.com