Written by Matthew Ponsford, CNN

Many architects now shaping the world's cities acknowledge a debt to Lego, the Danish toy company behind the plastic bricks that have littered bedroom floors for more than 50 years.

But in recent years, practicing architects and the multi-billion-dollar company have engaged in unprecedented collaborations to learn how the tiny blocks can spark new design thinking, on a miniature and grand scale.

Architects are informing a new type of Lego, and Lego -- and its enormous fan community -- is pushing the boundaries to create models that are imaginative but architecturally intuitive enough to encourage a new generation to learn how buildings are designed and constructed.

Lego launched its dedicated architecture range in 2008, which has grown to include landmarks like New York's Guggenheim Museum and Singapore's Marina Bay Sands, as well as a newer Skylines range, capturing cityscapes in Sydney, Paris and London.

Lego's Shanghai Skyline kit Credit: Courtesy Lego

Lego senior designer Rok Zgalin Kobe has the enviable job of transforming famous buildings into Lego kits, a dream role the Slovenian architect said had helped fulfill his childhood ambitions.

"As a young architect, you always want to build skyscrapers, whole cities even, museums and whatnot, but I wasn't too specific about the scale, apparently," he laughed. "I got the dream part, but on a table-top scale."

Kobe said the process of translating real architecture into bricks starts by getting into the mind of a building's original designer, then sitting down with architects' sketches and floorplans to understand how the building took shape.

This model of the LEGO House, the company's new visitor center, designed by architecture firm BIG, was a 'meta-model,' said Kobe, as the building itself was built to look like it is made of Lego bricks. Credit: Courtesy Lego

"Architects operate in grids and if you analyze these, in pen and paper over blueprints, then you can derive the best translation into Lego bricks," said Kobe.

The Lego version should not only resemble the real-life structure, it should tell a story about how it came to be built, he explained, using the example of the just-released model of the Empire State building. "If you know the real one, it was built using steel girders which were riveted together -- you know the iconic pictures where the guys are sitting on the giant beams?"

Lego's Empire State Building Credit: Courtesy Lego

Pulling away the model's facade, he revealed a replica of the steel skeleton inside the building. Below, there is a miniature reconstruction of the dramatic lobby that greets visitors from Fifth Avenue -- it is hidden away in the finished model, but seen by the Lego builder. "So behind the building's instructions booklet, while you're building, you have this little call-out that alludes to some of the features of the original."

In the newer Skylines series, there is much more "artistic liberty," Kobe said.

For San Francisco, the designers ignored real-world distances, using forced perspective to create something more like a caricature, that brings Alcatraz Island, the Golden Gate Bridge and the famous Painted Ladies row houses into a pleasing arrangement.

"It's a fake perspective. You have this collection of views," Kobe said. "It's all the little details, the tram on the hilly street and whatnot, that set the stage for the San Francisco."

From the adventurous to avant-garde

While whole cities are being given the official Lego treatment, dedicated fans of the plastic bricks are creating their own versions of famed buildings and local landmarks.

Tom Alphin, the author of "The Lego Architect," said fan-made kits are a big undertaking, with designers taking responsibility for everything from bulk-buying bricks and hand-dividing them into kits, to writing instructions and designing packaging.

Bought and sold at conventions or on Lego fan sites like Brick Loot, the fan-made world is a gray market of hazardous spikes and taboo "illegal connections" that force pieces together in unconventional ways. "The true custom fan kits can really go off the rails," said Alphin.

Villa Amanzi, Phuket, Thailand, 2008, Original Vision Ltd. Lego Model By Robert Turner. Credit: Robert Turner

Lego's official designers, Alphin explained, have to be wary of more than just architectural accuracy. They have to ensure that their designs meet Lego's house rules, including safety standards that ensure models don't impale a child falling on them, for example -- a serious consideration when working with skyline-dominating spikes like the Eiffel Tower and Seattle's Space Needle.

Designers of fan-made kits, however, are free to indulge their passions, no matter how niche, like the miniature Aarhus City Hall created by Danish architects Arne Jacobsen and Erik Møller, who used their skills to miniaturize the hall's distinctive clock tower.

Fans have also attempted ambitious architectural styles, like Norman Foster's high-tech HSBC building in Hong Kong to the Gothic curves of Paris' Notre Dame cathedral.

Nakagin Capsule Tower, Tokyo, Japan, 1972, Kisho Kurokawa. Lego Model By Matthew Allum and his daughters Akemie And Alleke. Credit: Matthew Allum

The curved lines of contemporary parametric architecture of the type designed by Frank Gehry, Zaha Hadid and Daniel Libeskind are a unique challenge for a system that sees the world in blocks, Alphin said. For Lego designers, these architects' works represent the greatest challenge -- "the cutting edge" -- he added.

One recent fan submission on the Lego Ideas website is an impressive attempt at the Milwaukee Art Museum, a criss-crossing, sail-shaped building by Spanish architect Santiago Calatrava that Alphin said has become a surprising test of mettle for Lego fan-designers.

Santiago Calatrava's Milwaukee Art Museum pavilion, a fan creation posted to LEGO Ideas by fan Vida Andras. Credit: Vida Andras/Lego Ideas

For fans hoping to try their hand, perhaps on something a little simpler to start, Alphin shared this tip: "Start by looking at the building, figuring out what the hardest part is going to be and building that first," he said. Everything else should then fall into place.

Community collaboration

The concept of using Lego bricks to inform future design was the subject of a recent exhibition, "The Cubic Structural Evolution Project," at London's Tate Modern gallery.

Danish-Icelandic artist Olafur Eliasson deposited a truckload of white building blocks in the Turbine Hall, the gigantic exhibition space at the center of museum, and invited people to build a "city of the future" along two 10-meter-long tables shaped like a map of London.

Olafur Eliasson's "The Cubic Structural Evolution Project" was at London's Tate Modern from 26 July to 18 August 2019. Credit: Tate/Joe Humphrys

By the second week, a giant pyramidal structure resembling North Korea's Ryugyong Hotel bore down over neighborhood of ornately textured skinny skyscrapers and a long cannelloni-shaped high-rise that looked like a futuristic hybrid of Chicago's Marina City and the Leaning Tower of Pisa.

"You have to be there almost all the time to see how it changes shape," said Mark Godfrey, Senior Curator at Tate Modern. "I sat there for an hour and watched people, and what's amazing is how different the types of structures are from the limited number of kinds of Lego brick there are at people's disposal."

While many Lego kits today focus on branded representations of anything from the Hogwarts Castle to the Millennium Falcon -- which might be built just once and never reassembled into any other form -- Eliasson stripped the experience down to basics, to see how communities make and re-make a built environment, said Godfrey.

Eliasson' white Lego city reached remarkable heights during the project. Credit: Tate/Joe Humphrys

For all the impressiveness of the true-to-life kits, that freedom to experiment without consequence is a solid foundation for the collaboration between architects and Lego.

Godfrey said the exhibition brought together people of all ages and backgrounds to celebrate the fun of Lego, as he remembered it as a child in the 1970s.

"You're free to build whatever you want," he said. "It's about creative building rather than following instructions."