You imagine that the headquarters of Lego will have been made using millions of primary-coloured interlocking bricks. The reality, alas, is quite the opposite: the second biggest toy company in the world, whose most recent annual profits were pounds 2.54 billion, is based in a series of unassuming buildings in the drizzly town of Billund, Denmark.
Inside, it's a different story. The ambience here is the very essence of Scandinavian cosiness (or hygge, as they say in Danish), with cheerful nods to Lego at every turn, from Lego sculptures and Lego candle-holders to the personalised Lego minifigures handed out instead of business cards by smiling employees.
"We've always said that Lego is more than a toy," says Jatte Orduna, head of the Lego Idea House. "It's a type of learning that uses both halves of the brain - structure and creativity."
Orduna has been here 15 years and is full of facts. For instance, there are 86 Lego bricks for every person on Earth. The products are on sale in more than 130 countries. More than two-thirds of British households have Lego. And based on their current growth, the population of minifigures will outnumber the population of humans by 2019.
The design studio - the company employs 180 designers - is very much off-limits; they're working on top-secret products that will hit the shelves in two or three years' time. Instead, Jatte takes us around the Idea House, an extensive exhibition devoted to Lego through the years that reveals just how much the toy has changed (as well as how much it hasn't - their first bricks still fit with the pieces produced today).
In the basement is an archive of every box since the early Seventies. "You get people crying here," says Jatte. "They see the set they had as a child, or that they wanted." Indeed, I spot a grey-haired granny, a precursor to the minifigure that I owned and loved.
The early sets were simple, consisting mainly of houses. Then the franchises poured in: Star Wars, Harry Potter, The Hobbit. One of the criticisms often lobbed at Lego is that the vast majority of today's sets encourage the building of a certain structure - be it the Star Wars Millennium Falcon or The Simpsons family house - with little opportunity for more creative play.
Lego, of course, don't see it like that. "When you're building something in particular, the child feels proud to have achieved it. But then we encourage the child to break it apart and make up something else using their imagination," says Jatte.
Those endless themed sets make smart business sense, though. "It's a struggle for us because we want to sell Lego, but the bricks last forever."
Another criticism is of its perceived attitude towards girls. A couple of weeks ago, a letter written by seven-year-old Charlotte Benjamin went viral. "I love my Lego," she wrote, "but I don't like that there are more Lego boy people and barely any Lego girls."
She had a point - currently 86 per cent of minifigures, the tiny characters introduced to encourage role play, are male. When Friends, the range targeted specifically at girls, launched in 2012, its pink-plastic stereotyping was met with howls of dismay from adult women. As Charlotte said: "All the girls did was sit at home, go to bed and shop and they had no jobs, but the boys went on adventures, worked, saved people… even swam with sharks."
Yet Friends sells by the bucket-load. Little girls clearly love the model pet salons and juice bars, while Olivia's House, one of the main character's homes, was Lego's best-selling toy of 2012.
Friends was four years in development and is Lego's most extensive research project to date. The company spoke to 3,500 girls - and their mothers - and discovered that girls prefer figures to look more realistic, so they can identify with them, as opposed to the traditional blocky minifigure.
"We also found that girls like details, things they can change around a lot, and things they have seen on TV, such as exotic destinations," says Jatte. "I know boys play with Friends, too, until they're five. Then there's a separation between the sexes."
Yet, seeing adverts from the Sixties and Seventies of boys and girls constructing the same buildings, you can't help but feel sad that girls today will be building a poodle parlour instead of a petrol station.
The great Lego gender imbalance might be about to change, though. This week, the first Lego film, The Lego Movie, is released. It's a charming tale of an ordinary minifigure mistaken for a "master builder" who has to save the universe. The film is clever, funny and touching - it will make grown men cry - and carries a strong pedagogical message: let Lego guide your imagination.
But the star of the piece, and the coolest character, is a girl. "Wildstyle is the real hero in this movie," agrees Matthew Ashton, vice-president of design and an executive producer of the film.
Matthew and his design colleague, Michael Fuller (both of whom, incidentally, are British - there are 20 nationalities working at Lego in Billund) worked closely with the Hollywood studio. Everyone involved wanted to make the film appear authentic, from the restricted movements of the minifigures - as if an invisible child's hand is guiding the action - to the fingerprints on the bricks.
"The message was particularly important for us," says Michael. "Every time the characters get into trouble, a creative building solution solves their problem."
Lego (the word comes from the Danish phrase leg godt, meaning 'play well') was founded in 1932 by Ole Kirk Christiansen, a carpenter from Billund, out of necessity. It was the time of the Great Depression and his wife had died, leaving him with four children. So Ole started making wooden toys. He moved into plastic after coming across Kiddicraft Self-Locking Bricks, a British invention by Hilary Page (who never lived to see the success of his invention; instead, his company received an out-of-court settlement of pounds 45,000 from Lego in 1981). Lego modified the bricks and patented the design in 1958. The brand launched in Britain the following year. The first minifigures were introduced in 1978 - a policeman and a nurse - and thousands followed. Their distinctive yellow faces are to make them ethnically neutral.
Given that Lego is now one of the most recognisable brands in the world, it is remarkable to think that, just a decade ago, the company was losing $1 million a day. The problem? Lego had diversified too much. The solution? Jorgen Vig Knudstorp, previously a management consultant with McKinsey, who became the first non-family member to lead the business when he took over from Kirk Kristiansen (Ole's grandson) in 2004. The Lego theme parks were sold off, products discontinued and the number of elements more or less halved.
To maintain the quality championed by Ole, Lego is still made in Billund - there are also factories in Mexico, the Czech Republic and Hungary. Inside the Billund factory, the vast floor space has been taken over by robots, 768 in all. Humans are only required for quality control. The precise engineering that ensures the pieces can be put together with a satisfying clink and pulled apart again with ease remains a closely guarded secret, while the bricks' studs work with a tolerance of a 200th of a millimetre - that's 10 times finer than the width of a human hair.
"We're constantly doing research with children," says Matthew. "We go into homes, watch children play behind two-way mirrors. And we discover things we would never have thought of - such as children being so detail-focused." Employees put on gloves to play with the bricks to better understand the motor skills of a five-year-old; and the company works with academics from Cambridge University and MIT on childhood development.
Play has changed over the years. "Children today don't have as much free time as they used to, due to sports and homework," says Jatte. "They have a schedule. They're not allowed to be bored."
Lego has its adult fans, too, who make up around 5 per cent of its sales. These include David Beckham, who recently revealed that he spends his evenings constructing grand edifices like Tower Bridge and the Taj Mahal.
The appeal is partly nostalgia, partly escapism. "People want their moment away from a computer and want a creative and tangible experience," says Jamie Bernard, a design manager who oversees the Lego Creator series aimed at the adult market.
Jamie, 38, is a true Lego geek. "Before I got this job, every night I'd come home and build. Then one day I was in a toy store and there were all these other adults. I asked the assistant who they were and was told they're the local Lego club. I joined on the spot! Before the internet, it was hard to find out about other fans."
Jamie visits fan events around the world - "They're doctors, lawyers, lots of architects and teachers" - and witnesses some amazing achievements, from life-size dinosaurs to the Brick Testament, which features 2,000 scenes from the Bible.
And no, they're not all men. One of the best builders is Alice Finch, who has created a sprawling Hogwarts Castle out of 400,000 bricks. "She's a rock star when she turns up to these events," says Jamie.
The company remains tight-lipped about its product plans for the future - although staff will admit that fans are pushing for Dr Who and Sherlock Holmes themes. There are plans to expand into China, too.
The possibilities are endless - as indeed are the possibilities with Lego itself. As Jamie says: "Think of the greatest works of literature, and they're made up of just 26 letters. Lego has 9,000-plus elements - just imagine what that allows you to do."
'The Lego Movie' is released on February 14.