May is one of the best times to visit this stunning Spanish city. A short trip over the May bank holiday allows you to avoid the summertime crowds, meaning you'll have a spot on the beach and can stroll along Las Ramblas and admire Gaudi's marvellous designs at leisure. Must-sees: the unfinished Sagrada Familia and the famous Parc Guell. A number of lowcost airlines fly London – Barcelona. Prices start from about £100.