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Ben Nilsson/Big Ben Productions

How to Build an Ice Hotel

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Ben Nilsson/Big Ben Productions

In the tiny arctic village of Jukkasjärvi, Sweden, dusk lasts most of the day at this time of year. Against the dramatic and ever-evolving pink and purple sky sits a structure that looks like a cross between a sleek nightclub and an igloo from outer space: Lapland’s storied IceHotel, the world’s largest and longest-running luxury hotel made entirely of frozen water.

A sprawling single-story structure built annually on the pristine banks of the frozen Torne River, the IceHotel is in its 23rd incarnation. In the late '80s, Yngve Bergqvist, who led white-water rafting trips on the Torne during the long arctic summers, invited some ice sculptors to create a winter river attraction. The result was an ice art gallery—a small igloo on the frozen river in which art work could be displayed. After a couple of years, an adventurous group asked if they could spend the night in the igloo. Afterward, they raved so much about the experience that Bergqvist decided to build a proper hotel. The first IceHotel was erected in the winter of 1989-1990. These days, it attracts 60,000 guests who want to spend a night in one of its 65 rooms. Of these, 15 are one-of-a-kind “art suites”—among this year’s are a UFO-themed room and a fairytale forest—designed and sculpted by visiting artists from all over the world.

Photo: Paulina Holmgren. Artists: Karl-Johan Ekeroth & Christian Strömqvist.

Staying in the hotel is kind of like camping out in a meat locker. The inside temperature is a constant 23 degrees Fahrenheit. Even the bedframes are carved ice—but a mattress, a reindeer pelt, and a sleeping bag make sleeping quite cozy. In the lobby’s Ice Bar, patrons huddle in heavy parkas, thick mittens, and snow pants. With the exception of a few cushions, every surface is gleaming ice—including the glasses in which the cocktails are served.

Photo: Ben Nilsson/ Artists: Åke Larsson, Mats Nilsson and Jens Thoms Ivarsson.

The hotel betrays a minimalist aesthetic that’s a hallmark of Scandinavian design. And the frozen architecture lends a serene quality even when the lobby is crawling with tourists. But when I visited on an impossibly clear and cold week this winter, the most remarkable thing about the place was going on behind the scenes: Amid the hustle and bustle, the IceHotel team was already quietly at work on the assiduous process of building next year’s hotel. It takes 1000 tons of crystal-clear ice cut straight from the river and 30,000 cubic meters of a pasty-white man-made mix of snow and ice that’s called, cutely, “snice,” to build the hotel each year. In a few months, everything from the king-size bedframes to the benches in the bar would be reduced to puddles—or, more precisely–reabsorbed into the river.


Building the ice hotel isn’t so much an annual process as a never-ending one. But if you had to specify a starting point for the endeavor it would be sometime in November, when the river freezes over. That’s when the production team, led by production manager Alf Kero, sections out a 14,000 square foot swath of ice with red plastic rods typically used to mark snow-covered roads. All winter long, Kero and his team will cultivate and monitor this patch—which will eventually become the raw material for the next year’s hotel.

An average of two meters of snow blankets the village over the winter, but workers plow this special patch of river with a front-end loader to keep it clear of precipitation. This ensures that the ice grows downward, into the still waters of the river below, rather than hardening upward. The result is ice that is crystal-clear, free from bubbles and cracks, and it’s this naturally formed glass-like ice that the hotel has made its trademark.

In December, during the weeks that the sun doesn’t come above the horizon, the entire river, which reaches depths of more than 60 feet, is frozen solid. Because of all that ice, the temperature in Jukkasjärvi can be 10 to 20 degrees colder than the nearby mining city of Kiruna, just 11 miles to the east. But by February, as the days are beginning to lengthen, the river is slowly beginning to thaw from its bed up. This is when the team begins to gear up to harvest the ice for the next year’s hotel, carefully monitoring its thickness. When it’s around three feet thick, usually in early March, it’s time for the harvest to begin.


The ice patch is gridded out into squares that measure roughly 20 square feet, and then the team slices the ice using a vertical saw mounted on a front-end loader, specially designed for the task by the team with the help of a local construction firm. Each cube, weighing nearly two tons, is lifted out of the river with a forklift. “The river flow is quite gentle in the area where we pick up the ice blocks,” Kero tells me, “but the ice can be slippery and at times it can be very windy so it is important to wear suitable safety equipment and ensure that the staff is trained and working in teams, never alone.” Altogether, the team harvests 5000 tons of ice this way.

Once a block is out of the river, the crusty top layer is sawed off, and then the blocks are sorted by clarity. The clearest of them are designated for use in the hotel rooms and to manufacture glasses—for the hotel's bar and three more Ice Bars the IceHotel runs, in Stockholm, Oslo, and London. During the summer, while the temperature outside reaches the 60s and the sun stays up all night, the giant blocks sit in two giant sub-freezing warehouses.

Seth Apper, aXcess Travel.

You can still visit the IceHotel in the summer—right now, the production team is busy building an IceBar and sample rooms that are open inside the hotel’s hangar-like art center each year. Once that’s done and the ice harvest has been completed, the team turns its attention to the planning of next fall’s hotel. “The first steps are a number of creative brainstorming meetings, where we set out the plans for the architecture and art,” says Sofi Routsalainen, a member of the Art and Design group, which oversees the production of the hotel. Over the summer, they’ll carefully choose the 40 artists who will create next year’s art suites from 200 applicants.


As winter begins to descend, it’s time to get ready to start construction on the new hotel. It takes a team of about 100 people—including builders, artists, lighting engineers, snice casters, tractor drivers, and the art and design group—to build the structure. In October, as the river begins to freeze, the production team prepares the grounds and wall moulds and makes sure electricity and sewage are in order, while they wait for the temperature to drop. A support wall is erected out of steel vaults.

Paulina Holmgren

When the ground freezes and there’s been a week of temperatures below 19 degrees Fahrenheit, it’s time to start spreading snice for the hotel floor. Snice acts like a paste and looks like the crust that builds up in a malfunctioning freezer. It’s made by pumping water from the river and blowing it through “snow cannons,” which results in tiny ice particles mixed with air. The substance is structurally stronger and more resistant to the sun than sheer ice, and has the insulating qualities of snow. A hotel built of pure ice would be much colder inside, and would melt quicker in the spring.

To construct each corridor of the hotel, a row of arch-shaped steel vaults are erected, and then sprayed with snice and left to set for a few days. Once they’ve frozen, the vaults are lowered onto skis and pulled out with a tractor. Internal walls are built using the same process. Once the corridor is divided into a number of rooms, doors are cut using a chain saw, and the LED lights are installed. (There’s no plumbing—if hotel guests have to use the bathroom in the middle of the night, they must venture to an attached warm building. Ask me about this some other time!) When the rooms are completed, the team stocks some of them with extra ice blocks—these will become the art suites.

Paulina Holmgren

For more than two weeks each November, the visiting artists chosen to create the year’s art suites work in the freezing rooms, using chisels and chain saws to carve the rooms they have planned. Then in early December, once the reception area, bar, and at least one wing of rooms are ready, the hotel officially opens for business. From then until the structure becomes unsafe to occupy in April, visitors will fill their days with ice sculpting lessons and snowmobile sojourns. They might even attend one of the 150 weddings celebrated each year in the ice chapel. As for the nights: those are spent out on the frozen Torne, watching for the Aurora Borealis—and learning the value of a good down sleeping bag.

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Creative Bar Owners in India Build Maze to Skirt New Liquor Laws
June 20, 2017
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Facing a complicated legal maze, a bar in the southern Indian state of Kerala decided to construct a real one to stay in business, according to The Times of India. Aiswarya Bar, a watering hole that sits around 500 feet from a national highway, was threatened in 2016 after India's Supreme Court banned alcohol sales within 1640 feet of state and country-wide expressways to curb drunk driving. Instead of moving or ceasing operation, Aiswarya Bar's proprietors got creative: They used prefabricated concrete to construct a convoluted pathway outside the entrance, which more than tripled the distance from car to bar.

Aiswarya Bar's unorthodox solution technically adhered to the law, so members of the State Excise Administration—which regulates commodities including alcohol—initially seemed to accept the plan.

"We do [not] measure the aerial distance but only the walking distance," a representative told The Times of India. "However, they will be fined for altering the entrance."

Follow-up reports, though, indicate that the bar isn't in the clear quite yet. Other officials reportedly want to measure the distance between the bar and the highway, and not the length of the road to the bar itself.

Amid all the bureaucratic drama, Aiswarya Bar has gained global fame for both metaphorically and literally circumnavigating the law. But as a whole, liquor-serving establishments in India are facing tough times: As Quartz reports, the alcohol ban—which ordered bars, hotels, and pubs along highways to cancel their liquor licenses by April 1, 2017—has resulted in heavy financial losses, and the estimated loss of over 1 million jobs. Aiswarya Bar's owner, who until recently operated as many as nine local bars, is just one of many afflicted entrepreneurs.

Some state governments, which receive a large portion of their total revenue from liquor sales, are now attempting to downgrade the status of their state and national highways. To continue selling liquor in roadside establishments, they're rechristening thoroughfares as "urban roads," "district roads," and "local authority roads." So far, the jury's still out on whether Kerala—the notoriously heavy-drinking state in which Aiswarya Bar is located—will become one of them.

[h/t The Times of India]