This problem was compounded by the fact that while I had the 'tune', I had none of the words - apart from 'Barcelona', of course. I thought that if I chucked in a few of my own, perhaps the bloody refrain might just go away. So I began with 'Barcelona . . . so good they named it twice', and somehow ended up with something that 'cleans a big, big carpet for less than half-a-crown'.
Having a daft song spooling around my brain, however, turned out to be not a bad accompaniment for a wander around what can be a pleasantly daft city.
Start with Las Ramblas, for example, where the first person I encountered was a man in his fifties, dressed in football kit clearly designed for a boy of about seven. From what I could make out of his handwritten sign (my Spanish stopped at O-level), he was hoping to get into The Guinness Book of Records for juggling a football from foot to foot (I think the sign said he was aiming to do it for a couple of weeks - but this may have suffered somewhat in translation).
The astonishing thing about this herculean endeavour was that no one on Las Ramblas seemed terribly bothered. I think the worry was that, if you showed too much interest, the poor bloke might lose concentration, with awful consequences.
If it was concentration he was after, Las Ramblas - among the tortoise-sellers, fortune-tellers, shoe-shine boys, canary vendors, florists, 'find the lady' tricksters and purveyors of hard core pornography - was a daft place to be. But then, that's Barcelona ('so good they named it twice'). Weekend breakers may make Las Ramblas their first port of call in Barcelona, but the second is certainly the Picasso Museum, housed in a couple of handsome Gothic palaces. The painter spent an important part of his life in Barcelona - from the age of 14 to 23, which included his Blue Period.
The museum may have few of Picasso's well-known works - Guernica, for example, is in Madrid - but it is a stunning collection, nevertheless, which shows his extraordinary development as an artist: from early competent but unremarkable youthful sketches to his impressive studies on a theme by Velasquez.
The only wearing aspect of the museum is that it tends to fill up with coach parties of people 'doing' Europe. Two elderly American ladies were pondering one of the Harlequin paintings. 'Perhaps we could get it from the gift shop,' said one. 'What? A print of this?' croaked her friend in horror. 'No, that Picasso perfume: Paloma. You know.'
'He made perfume, too? Some hell of a guy, Peggy.'
Barcelona's other must-see cultural attraction is the work of architect Antonio Gaudi. I felt about Gaudi the same doubts as I have about Salvador Dali: man of genius - or just daft as a brush? A visit to Gaudi's best-known work, the Sagrada Familia church, pushed me into the 'man of genius' camp.
I knew that the church was unfinished; I had not realised quite how unfinished - it is more building site than place of worship. All that exist are the walls and the spires, though these amount to rather a lot.
A climb to the top of one of the eight spires is not lightly undertaken, but is recommended in order to have a close look at the extraordinary detailing that reveals Gaudi's trademark of organic forms. The sunflower tops to the spires are like a joyful shout of praise, irrepressible and, well, slightly daft.
Having enjoyed the Sagrada Familia, you will probably wish to seek out the other famous Gaudi buildings: the Casa Mila or La Pedrera, on Passeig de Gracia, with its extraordinary flowing balconies; the Casa Batllo, also on Passeig de Gracia, with its eye-catching ceramics; and Palau Guell near Las Ramblas. Also worth the trip is the Gaudi House Museum in Parc Guell, with its gingerbread houses and dragon slides.
In contrast to his exuberant architecture, Gaudi's death was improbably bleak: he was run over by a tram in 1926. Once something of a dandy, he had become a virtual recluse, and was found at the scene of the accident with no socks, his jacket held together by safety pins. A fascinating exhibition on his life and work in the crypt of the Sagrada Familia shows that almost the whole of Barcelona turned out to join his funeral procession. (Hard to think of the death of a modern British architect that would provoke a similar public display of grief.)
Shortly after Gaudi's death, Barcelona was plunged into the sort of social turmoil familiar today from newsreel footage of Bosnia. In 1931, a Catalan republic was proclaimed in Barcelona, and for the next eight years, until the city fell to Franco's fascist army, it was riven by faction fighting between assorted groups of socialists, Communists and anarchists (a struggle wonderfully recorded by George Orwell in Homage to Catalonia).
Barcelona's resurrection as one of the great cities of Europe was completed two years ago, when it hosted the 1992 Olympic Games. It is worth taking a trip up the hill of Montjuic just to take a look at the Olympic stadium.
The Joan Miro Foundation is to be found here; there is also an amusement park, as well as a Spanish village that contains examples of architecture and craftsmanship from all over the country.
I finished my visit to Barcelona down at the bottom end of Las Ramblas, next to the harbour, looking up at the huge Columbus monument, topped by a statue of the great explorer pointing out to sea. The statue was erected for the universal exhibition of 1888, when it was argued that Columbus was really a Catalan (a hopelessly daft idea).
A new tune popped into my mind: 'They all laughed at Christopher Columbus when he said the world was round . . .' Grateful to be free of Freddie Mercury, I trotted back up Las Ramblas to see how the football juggler was doing. On second thoughts, not daft, I decided, but deft.
Getting there: Return fares from London to Barcelona with British Airways (0345 222111) and Iberia (071-830 0011) cost from pounds 157 (stay must include a Saturday night).
Packages: Kirker Travel (071-231 3333) is offering three-night B & B packages to a four-star hotel from pounds 269.
(Photograph and map omitted)