He is known as the French Banksy – or simply JR. Now the artist popular across France for large-scale projects, from photographs to graffiti and street art, wants Parisians to do something unusual on what is arguably the city’s most famous bridge: stop. In June, he plans to transform the bustling Pont Neuf that dates back to the 17th century into a walk-through “cave” – a temporary, monumental pub...