On the right lines in Nantes: giant sculptures, fantastical gardens and ancient castles

In 2027, the world's greatest "urban tree" will take root in a magical garden at the heart of a black granite quarry in France , about 50 kilometres from the Atlantic Ocean. Towering 35 metres in the air and with 22 branches, The Heron Tree will be home to birds, ants, sloths, caterpillars, hummingbirds, spiders, butterflies and geese. But this is no ordinary tree. The animals that live on its leaves and among its roots will be mechanical creatures that visitors can interact with. From chameleons you can ride on, to caterpillars that need a driver, and passenger-operated spiders or birds that carry people in baskets attached to their wings, the tree's animals and topiary will be crafted from thousands of tonnes of steel. The fantastical project is being brought to life at The Extraordinary Garden — a place that's already home to walking paths, a 25-metre high waterfall and several viewpoints. All this is the work of Les Machines de l'Ile, a company that's been largely responsible for giving Nantes’s old docks a new lease of life. It's also been a key player in the capital of the Pays de la Loire region's move to shake off its 20th-century scars and craft a name for itself as a revitalised, creative and cultural metropolis. About a two-hour train ride from Paris , Nantes was as at the heart of the French Resistance during Second World War and suffered badly for it. It was also separated from Brittany — a region it was once the capital of, and has never returned to the fold. With its relatively short-lived success as a shipbuilding hub in the 1950s and 1960s, the city began to heal its war wounds, but just as it was recovering, it was hit hard by global restructuring in the 1970s. Unemployment rates rocketed when Nantes’s last major shipbuilding site closed in 1986. But the city is experiencing a renaissance and Les Machines de l'Ile's imaginative works have been a fundamental driver in the distinct change of pace in this now vibrant city. The Heron Tree aside, the geniuses at the mechanical works company are also responsible for Nantes’s biggest tourist draw — The Grand Elephant. Located opposite the Loire river, this four-storey high mechanical mammal carries up to 50 people at once inside an eight-metre-wide body. Based on the writings of Jules Verne , author of Twenty Thousand Leagues Under the Sea and Nantes’s most famous literary son, the elephant found its home in the city in 2007 and attracts visitors from across France and beyond. A whopping 21 metres in length, the steampunk-style creature is made of 49 metric tonnes of steel and wood, and trundles along a repurposed warehouse, spraying water out of its mechanical trunk. It is in Ile de Nantes, the area hardest hit when the city’s shipbuilding works ceased. This area has since evolved into Nantes’s cultural hub, and is home to some of the most popular stops on the city’s Green Line walking tour. Stretching over 12km, the Green Line is a year-round trail that leads visitors around Nantes's best attractions. Taking in cultural elements, tourist sites, major monuments and plenty of hidden treasures, it highlights everything the port city has to offer. The island is a good place to start the tour as it's also where you'll find Le Carrousel des Mondes Marins, another engineering marvel by Machines de l'Ile. This 25-metre high, three-tier grand carousel is an intricate merry-go-round filled with sea sculptures that takes riders on a whimsical journey over the ocean, with nostalgic nods to the past. A basketball "tree" designed to allow several people to shoot hoops at once, a contemporary arts venue housed in an abandoned 1940s hangar, zigzagging zebra crossings and giant white head sculptures are also to be found while walking the line in this district. As it leads towards the Manny building, named after the woolly mammoth in Ice Age, passers-by can stop and listen to Air — a public work by sculptor and musician Rolf Julius that combines the sounds of clinking metal and distant bird song. In the historic old city, follow the painted streak through a medieval cavern of cobbled streets and spire-topped cathedrals, leading visitors to the Chateau des Ducs de Bretagne — perhaps Nantes's most important building. Seven towers make up this turret-decorated castle, which was the former residence of the Dukes of Brittany and Anne of Brittany — the only woman who was ever Queen of France twice. Further west, the line leads to Graslin, Nantes’s most opulent neighbourhood and a spot that's visible from almost anywhere in the city thanks to the tall white spire of its Basilique Saint-Nicolas — a neo-Gothic church that dates back to 1854. Known for its upscale restaurants, boutique-filled streets and monumental fountains, this is also where you'll find Passage Pommeraye, one of Europe’s most beautiful covered arcades, which were a precursor for today’s shopping malls. Built in 1843, the flamboyant building has an elaborate staircase, ornate cherubs, statues and a maze of gilded galleries. At the end of the arcade, on the lower floor, is Maison Georges Larnicol, one of the city’s most famous biscuiterie chocolateries. Famed for its gateau nantais, an almond cake that's a Nantes speciality, the store is also to blame for the irresistible sweet scent of pastries that wafts through the passageway. Nantes is a city that’s known for its sweet tooth, so it’s no surprise to find a long list of desserts on the menu at nearby La Cigale, a brasserie and listed historic monument famed for its Art Nouveau interiors. A former rendezvous spot for Surrealist artists such as Andre Breton and Jacques Prevert, a visit here is akin to stepping back into a slice of French bourgeois history. Just across the courtyard, you'll see L'Univers Cafe, one of the oldest bars in Nantes. Having opened as a speakeasy jazz lounge in 1852, it still hosts regular performances. Visit at aperitif hour when seating spills out towards the Place Graslin, giving visitors a front-row seat in the shadow of the Pantheon-like neoclassical Graslin Theatre and its eight Corinthian columns. A few steps away is the century-old Kartoza, Nantes’s oldest cinema, and Oceania l'Hotel de France Nantes, an 18th-century private mansion that now offers elegant lodgings in the heart of the district for travellers who want to linger here a while longer. Perhaps one of the most important stops on Nantes's Green Line is the plant-covered walkway on Quai de Loire. Created by Krzysztof Wodiczko as a memorial to the abolition of slavery, it acknowledges the city's role as France’s biggest slave-trading port. Shining a light on the city’s shadowy past, when an estimated 500,000 Africans were ferried to the Americas involuntarily, it consists of 2,000 commemorative plaques inlaid with the names of the ships that departed from Nantes with captives on board. These have been laid within a meditative promenade marked with quotes on the subject of slavery. The hauntingly beautiful site is the only memorial of its kind in Europe, and is designed to keep the memory of the past alive, and serve as a warning for the future. In Cours Cambronne park, wander through private courtyards in one of Nantes's most affluent residential areas. Stop to take in the Eloge de la transgression , a quirky sculpture by artist Philippe Ramette that depicts a schoolgirl climbing on to an empty pedestal. Or is she climbing off? It's apparently all a matter of perspective. Whichever way you see it, it’s obvious to all that the hundreds of freely accessible public artworks in Nantes are a key part of its redevelopment. Other highlights dotted along the line include Nymphea, a video projected artwork that floats on the surface of the canal; Le Temps, where artist Flora Moscovici has transformed a 15th-century chimney into a pastel dipped artwork, and Metre a Ruban , a supersized measuring tape by French artist Lilian Bourgeat. Families will enjoy a visit to Aire de Jeux, where a bamboo sea monster acts as a playground, and the creature’s giant tongue is a fully-functioning slide. And as you wander the line, remember not to simply look down. One of the most beautiful aspects of this trail is that there’s something to see at every turn, large or small. A concealed micro-tropical garden blooms with palm trees, cacti and flowers in an alleyway off one of the main streets, while historic gargoyles adorn the ledges of terraced houses. Look out for the artist-designed retail signs that hang above the doors of sweet shops, pharmacies and fromageries, and don’t miss the small entrance of an artist-designed three-storey micro home, accessible only by ladders and denoted by a cluster of origami cranes dangling above an ancient passageway. The Green Line route evolves every year as new exhibitions, street shows and installations are added to it, meaning it's never quite time to draw a line under Nantes. This season, two new permanent artworks opened among the graves of the city's oldest cemetery, which, much like the city's own transformation, has breathed new life into a place that had been all but forgotten.

On the right lines in Nantes: giant sculptures, fantastical gardens and ancient castles

A two-hour train ride from Paris, the capital of Pays de la Loire throngs with chocolatiers, culture and creativity, all reachable via a 12-kilometre walking trail painted on the pavement