Barcelona is a great destination for gravel cycling. Well, it is a great destination for any kind of cycling, but as it is a big city, road cycling can be a bit stressful for those not used to cycling sharing the roads with cars.
The mountains surrounding Barcelona are beautiful, with plenty of gravel paths, and hidden tracks to enjoy cycling at its best. The Collserola range of mountains, which highest point is Tibidabo, has a lot to offer to those who love cycling. The highlight is possibly the so-called Carretera de les Aigües (translated from the Catalan language: water road). It is a 10 km long path overlooking the city. An amazing balcony from which you can see the whole city.
But it is not only the mountains surrounding Barcelona. Also very interesting is Serralada Prelitoral, leading north Barcelona, with big amount of mountain paths to enjoy with a gravel bike. Another nice path follow river Besos on the north part of the city and also following Llobregat river on south.
A very nice option for gravel bikes is linking Barcelona with Girona. This nice town north Catalonia has become one of the biggest cycling destinations in the world. Especially for road cycling but also for gravel cycling.
No need to say that the nice weather all year long makes possible to do the gravel routes from January to December. Great experience!