And, listening to this obsessive man fielding questions about today's wrap calls to mind a scene in Mel Brooks's movie The Producers, in which a comic-book Nazi, author of "Springtime for Hitler", explains to Max Bialystock (one-time King of Broadway) and Leo Bloom (bent accountant and co-producer of what is planned to be Broadway's biggest flop) why the Fuhrer was a better artist than Churchill (war leader and watercolourist).
"Hitler," says the Nazi, his voice rising in a spitting crescendo, "there was an artist... he could paint an entire apartment, one afternoon, two coats." It is easy to imagine him saying, "Christo, there was an artist... he could wrap an entire Reichstag, one afternoon, two sheets."
"Not exactly one afternoon," Christo says in his unreformed Bulgarian accent, looking down from the roof of the Reichstag. "If all goes well, and the weather holds out, we will lower these 100,000sq m of fabric - 70 sheets - in stages over the parapets of the building, tying them with 15,600m of blue polypropylene rope as we go. The spectacle should finish on 23 June, a total of between five and six days. The Reichstag will stay wrapped for two weeks and then... poomph, the fabric will disappear and everything will be the same again." Or not.
Christo and Jeanne-Claude, his wife, collaborator and the woman who has finished many of his sentences for the past 37 years, have been wrapping, or thinking about wrapping, buildings for almost as long. Like all obsessives, Christo started in small ways. He wrapped a girl in London in 1962 ("Wrapping a Girl, London 1962"), followed by a tree in Eindhoven in 1966 ("Wrapped Tree, Eindhoven 1966"). Girls and trees led on to fountains, public monuments and, finally, buildings; first, the Kunsthalle in Berne in 1968, then the Museum of Contemporary Art, Chicago, the following year. Whole valleys and coastlines followed. Whatever next? Today, the Reichstag, tomorrow...
These projects might sound megalomaniacal, but nothing could be further from the truth. Christo and Jeanne-Claude's works might be bombastic and heroically pointless, but they are also consistently delightful, funny and humane. Occasionally, the joke backfires on artist and dealer: Christie's staff in London relate the tale of the day a porter unwrapped a small Christo, wondering why there was nothing in it but an empty picture frame.
Christo and Jeanne-Claude would have found this funny too. In fact, their artistic credo is one of rescuing art from snobbery, galleries and museums, taking it into city streets or the countryside for anyone to enjoy. Today's wrapping of the Reichstag ("Wrapped Reichstag, Berlin, 1971-95"), however, has been the hardest project they have tackled and the most politically sensitive.
"The project began in 1971," says Christo, "when Michael Cullen, an American art-dealer friend of mine in Germany, sent me a postcard of the Reichstag from Berlin. I wanted to wrap it straight away. Of course, the Reichstag has great significance - a meeting point between East and West, democracy and totalitarianism - and, now, it represents the heart of a democratic and united Germany at the centre of a Soviet-free Europe. In 1971, none of us expected the Berlin Wall to fall or the Soviet empire to collapse. The project has taken on some kind of significance, but we've never intended it to be anything other than something beautiful to look at."
Art for art's sake? "If you want. The German press wanted to know the precise philosophical reasoning behind the project. Of course, there is none. I said it will be like a mirror, reflecting whatever you want to see in it. You do not need to be a critic to understand what we're doing. In fact, there's nothing to understand."
"It's there," says Jeanne-Claude - a shock of dyed red hair, a slash of red lipstick, and a wickedly funny tongue - "because we wanted to see it for ourselves. But, like you and the German press, we haven't seen it, except in our minds' eye and in Christo's drawings."
Christo has been making drawings, collages and models of the wrapped Reichstag for 24 years. These have been sold to pay for the project. Every last pfennig. Christo and Jeanne-Claude have always refused subsidies. "We earn money through our art to invest in our next works. This leaves us free technically as well as spiritually. No one can own us or own our wrapped works, no matter how rich. No sponsor can gain social cache from a Christo. There is no charge for admission to see them, because there is nothing to be admitted to. The Reichstag is simply there, but looking a little different."
So, a Christo project comes with no strings attached (aside from a few miles of brightly coloured rope). The wrapping of the Reichstag costs Berlin nothing, and, because of the way the pounds 4.5m project is being tackled, it will not interfere with everyday life in surrounding streets. When the fabric is rolled up, chopped up and sold on to a variety of manufacturers (there is never any waste after a Christo wrap), there will be no physical trace of this extraordinary artwork. There will, however, be the lithographs (signed and unsigned), postcards, books and miles of film and videotape. These, and one million one-inch square souvenir pieces of the silver fabric, packaged like chunks of the Berlin Wall.
So, why has the wrapping of the Reichstag taken so long to achieve? Because several generations of German politicians, Chancellor Helmut Kohl the most vocal, have felt that the project would demean the building (designed by Paul Wallot and completed in 1894) and thus German government and Germany itself. But, would the British Government ever have given assent to the Palace of Westminster being wrapped? The French parliament turned Christo down as long ago as1961, although the City of Paris allowed the artist to wrap the Pont Neuf in 1985.
To date, the Christos have made 54 trips to Germany to prepare the way for the Reichstag wrap. Ten of these have been to discuss the project individually with nearly every member of the Bundestag, the German parliament in Bonn.
Despite the endorsement of the late Willy Brandt, Christo was turned down three times between 1977 and 1987. Finally, in February 1994, the Bundestag met to vote on the issue. "This was the first time," says Christo proudly, "that a full parliamentary session has been called anywhere in the world to debate the creation of a work of art." The debate lasted 70 minutes, with Chancellor Kohl muttering that the wrap would go ahead only over his dead body. The Bundestag voted 292 in favour, 223 against with 9 abstentions and one wasted vote. The Chancellor is alive and well.
With parliamentary approval, the Christos went into top gear, setting up an office - Verhullter Reichstag GmbH - in the shadow of their target. Sir Norman Foster and Partners, the English architects in charge of the restoration of the Reichstag, share the same building on Ebertstrasse. From here, a team of architects, engineers and technicians has planned and organised today's event. Meanwhile, seven factories in former East Germany have been making the fabric. Altogether, some 240 professionals and 1,200 volunteers will have been involved in the project.
Has the wait been worth it? "It's like a long pregnancy," says Christo, "and as pregnancy is part of having a child, so are all these years of drawings and discussions. Or, you can say that we have come out of the software part of the project and into the hardware."
What will the Christos be doing today? "Screaming at each other, as usual," Jeanne-Claude says. "And praying for good weather." "Most of all," Christo says, "we will be excited to see what it looks like."
And, then what? "On to the next project," says Jeanne-Claude. With no rest in between? "We haven't had a holiday in 37 years; we're always working," says Christo. "No," corrects Jeanne-Claude. "We did book five days on a little island some years ago. But by day three we were completely bored and missing New York." Not exactly laid-back then, the Christos. "We don't want to be," says Jeanne-Claude.
They have been working hard without going off the boil since they met in Paris in 1958. Christo (born Christo Javacheff, 13 June, 1935 in Gabrovo, Bulgaria) is the son of a chemist and general secretary of the Sofia Academy of Fine Arts. He enjoyed a classical art training in Sofia. "The studies were useful in one way," he says, "because we spent four years at the Academy studying architecture, town planning and engineering as well as drawing and painting. Projects like the Reichstag mean working with experts in these disciplines. We understand one another pretty well.
"But, the political regime was, of course, oppressive and Bulgaria completely out of touch; in fact, the only famous thing that came to us in those years was the Orient Express; I wanted to be on that train going west." Christo left for Paris on a goods train, he says, while on holiday in Vienna.
In Paris he painted portraits. One of his clients was General de Guillebon, a French war hero. Christo married his daughter, Jeanne-Claude. Jeanne- Claude was born in Casablanca, on exactly the same day as her husband. They have been working together ever since, and, although this has made them nominally wealthy, Jeanne-Claude insists that the money they make is wrapped up almost entirely in future projects.
Future projects, like the Reichstag, can be very long-term and extraordinarily expensive. For the past 15 years they have been planning to erect 11,000 fabric gateways in New York's Central Park, a 27-mile-long work of art that can hardly come cheap. And, since 1992, they have been working on a plan to cover several miles of a river somewhere in the western United States in wave-like folds of fabric.
Perhaps because these extended artworks cost no one except the artists a penny, sous, cent or pfennig, the popular press chooses either to ignore the Christos, or represents them as harmless eccentrics. Batty or not, the artists have proved over and again that they can connect with large audiences. They neither pontificate nor do they erect conceptual barriers.
When Christo does attempt to rationalise his work, the result is refreshingly straightforward, naive almost. "Throughout the history of art," he writes, "the use of fabric has been a fascination for artists. From the most ancient times to the present, fabric, forming folds, pleats and draperies, is a significant part of paintings, frescoes, reliefs and sculptures made of wood, stone and bronze. In the Judaeo-Christian civilisations, as in weddings and other ritual celebrations, veiling has had a sacred and joyful message. The use of fabric on the Reichstag follows the classical tradition." Or perhaps it follows Surrealists like Man Ray, who were exhibiting wrapped objects 30 years before Christo's odyssey in fabric. But, none of this will matter in Berlin today, when, weather permitting, "the silvery richness of the fabric will create sumptuous folds highlighting features and proportions of the building and revealing the essence of the Reichstag." Keep on wrapping, Mr Javacheff.