Seeing how a Spanish sparkling wine is made was a Barcelona highlight for Gillian Vine.
It was the black bottle that first attracted me to Freixenet's Cordon Negro cava. The pleasant any-occasion bubbly appealed, so my impulse buy was worth the punt.
Popular not just in Spain but around the world, the wine is exported to 140 countries, including New Zealand.
In 2012, we drank 48,000 bottles of Freixenet cava but we lagged far behind Australia, whose consumption last year was expected to top 250,000 bottles.
Apart from knowing cava was the Spanish equivalent of Champagne, I never had given any thought to its origins, so I jumped at the chance to tour the company's headquarters.
My ''significant birthday'' present to myself had been a voyage from Rome to Malaga in Spain on the Seadream 1, a small five-star vessel.
On board was an Australian wine writer, who had handled Freixenet's public relations in Australia, and he suggested several of us join him for a winery visit while Seadream 1 was docked in Barcelona in northeast Spain.
When Freixenet was set up, it was out in the countryside, 40km from Barcelona. Since then the city - Spain's second largest, with the Greater Barcelona population now some 4.5 million - has expanded so much that the 40-minute drive to Freixenet was not one of the empty rural vistas I expected but lots more houses and factories than paddocks.
Cava may, by law, be produced only in designated areas, mainly Catalonia, the area surrounding Barcelona, and the total area growing grapes for it is 26,000 hectares.
Now the world's biggest producer of sparkling wine using traditional methods, the Freixenet group produces 200 million bottles a year.
A fifth-generation family business, employing 1300 people, the company was formed 150 years ago, following the marriage of Dolores Sala Vive and Pedro Ferrer Bosch, members of families with long-established winemaking histories.
It now has subsidiary interests worldwide, including Coonawarra Katnook estate in South Australia.
In Spain, Freixenet has 350ha of vines plus 1200 contractors supplying additional grapes to bring its annual intake to 60 million kg.
The harvest ended a fortnight before our visit in mid-October, although the subsidiary crop, olives, were still to be gathered.
It would have been interesting to see the pickers as work, as 95% of the grapes are still hand-picked to ensure quality: machines can't tell ripe from green or pass any blemished fruit.
A few golden-toned Macabeo remain, sweet enough to nibble like a table grape while walking around the vineyard.
With Parellada - ''It makes lively wines,'' I'm told by Freixenet executive Jeb Bargallo - and Xarello, Macabeo is one of the three main white varieties used in the company's cava.
The soil, clay and sedimentary stones indicates that this is an old riverbed but there's no trace of moisture, as the autumn rains are late.
The wettest month here is October, when most of the region's annual rainfall of 500mm has always come soon after the harvest, softly wetting the ground.
In recent years things have changed, though, for not only is the wet season later but rain comes down in torrents that rip through the site.
Because the vines are grown without irrigation, changing weather patterns are of concern, not only at Freixenet but throughout Catalonia.
The vines on this site are a mere 45 years old, all grafted on to the best available phylloxera-resistant American rootstock.
Although copper sprays are applied, in keeping with the European Union's push to lower the use of agricultural chemicals pheromone traps are used to control insect pests, especially the European grapevine moth, Lobesia botrana.
The trap system has been used for the past 12 years and 90% of Freixenet's contractors also use it.
The cost in euros is ''similar to chemicals'' but the ecological benefits are enormous, as ''the company is committed to finding organic solutions to any problem'', Jeb says.
As well as the familiar black-bottle Cordon Negro, of which 50 million bottles are produced annually, the Freixenet cava line-up includes its superb top-of-the-range Reserva Heredad made from Macabeo (67%) and Parellada (33%) grapes, and a delicious pink cava, Trepat, named for the black grape variety used.
Alas, of the 30,000 bottles of Trepat produced annually, none is exported.
Each year, 80,000 visitors pay a 6 (about $NZ10) entrance fee to tour the Freixenet complex.
We do an extended version of the tour, tootling around the 20km of cellars, thankful for transport in a small motorised train, although I'd rather hoped to be riding one of the bottle-shaped vehicles parked outside.
Jeb's unerring sense of direction is a relief, as the complex is maze-like to the uninitiated, while the mix of modern bottling and packing systems and old web-covered bottles make interesting contrasts.
For cava, the character depends on fermentation techniques, typically at low temperatures (14 to 16degC) to retain the natural grape aromas.
Fermentation yeasts come exclusively from the company's own strains and after the second fermentation in the bottle, the necks are frozen, so the lees can be removed before the bottles are corked and wired.
A query about whether there is any thought of changing from corks to screw caps makes Jeb shudder.
A big part of the appeal of a good sparkling wine is psychological, that distinctive pop as the cork is pulled.
A bottle of Freixenet cava is opened and we sigh in anticipation.
Jeb's point is made.
