Outside, dusk approaches and streetlights slowly flicker to life. Perched at my computer, I watch a live webcam feed from Stockholm; the on-screen scene resembles the one outside my own window, but shows a tall tower against the darkening sky. Its windows gleam with vivid colors, ranging from red to blue to green – and everything in-between. I call the number below the feed and, by pushing a series of digits, turn each of the tower’s windows a glowing red.

But before we proceed any further, let us delve a little deeper into the tower’s intriguing history. In 1878, Lars Magnus Ericsson started to make and sell his own telephones and soon branched out into telephone exchange switchboards. Thanks to his company’s valiant efforts, Stockholm soon had more telephone subscribers than any other city around the world.

The Telefonplan tower lit up at dusk
The Telefonplan tower lit up at dusk

In 1936, work started on the Ericsson manufacturing complex and headquarters in Hagersten, Stockholm. Sometime during the 1940s, the seventy-meter Telefonplan Tower joined the campus to facilitate microwave technology experiments.
Early this millennium, the Ericsson company relocated – and the Telefonplan Tower was abandoned. Mobile technologies had advanced in leaps and bounds, no longer requiring those microwave testing grounds.

The building’s new use and ‘inhabitant,’ the light installation Colour By Numbers, is the brainchild of interaction designer Loove Broms, artist Erik Krikortz, and architect Milo Lavén. Paying homage to the tower’s history, the three artists decided to create a phone-based light installation in the empty Telefonplan premises, throwing the switch on their project in late 2006. Once again, the tower came alight and alive, treating Stockholm’s residents to a brightly colored, seemingly erratic display with an eerie life of its own.

A screenshot of the tower from the Colour By Numbers livestream
A screenshot of the tower from the Colour By Numbers livestream

As soon as locals realized the machinations behind the irregular switching behavior – and their own option to get involved – they started to call the tower en masse. By now, “most people know about the artwork, but you can certainly still surprise the odd person. We have heard stories of people using it as a party trick,” add the artists behind it all. Visible to most of south-western Stockholm, Colour By Numbers has become so well-known that it even graces two major works of literature: young adult novel Här ligger jag och blöder (2010) by Jenny Jägerfeld where “the light installation appears many times and carries a certain symbolic level for the plot,” according to Krikortz, and Arne Dahl’s Himmelsöga (2007), in which “the serial killer interacts with the light installation on several occasions, always coloring it blood red. The killer detests ordinary people who mix up the colors.”

So, how does it actually work? The windows of the tower’s uppermost nine floors are illuminated by red, green, and blue LEDs. Callers first select the floor or floors they would like to manipulate by selecting the corresponding digit(s), i. e. a number from 1-9. A separate setting allows them to tweak the intensity of the red, blue, and green LEDs, enabling people to mix several shades of the RGB color wheel. While ‘1’ decreases the amount of red, ‘3’ will boost it – and if all three colors are turned up all the way, the chosen window simply turns white.

On average, the tower - which is illuminated by red, green, and blue LEDs - gets 24 requests per night
On average, the tower – which is illuminated by red, green, and blue LEDs – gets 24 requests per night

On average, the tower gets 24 requests per night, with about half of the calls originating from Sweden itself – possibly watching the changes live – while the other half comes from abroad, i. e. from fans viewing the installation via the live feed on the Colour By Numbers website.
Ready to up their game, the artists are about to release a dedicated web app to give people an alternative tool for controlling the lights.

The tower has become so popular and renowned that there is even a PhD thesis based on the project: Linda Ryan Bengtsson’s research analyzes tower interactions. She found that online viewers usually focus on short light “performances,” while local viewers tend to have longer-term relationships with the tower – they might call if no one has changed the colors for a while because the building looked ‘lonely.’ Some viewers even have their own signature light design: One user creates the same display on his daily commute to let his wife know that he is on his way while another waits for trains to pass the bottom of the tower to delight them with a changing look.
Bengtsson’s research reveals that people interact with the tower in the knowledge or hope that passers-by and residents will notice their interventions; they express a desire for direct involvement in their immediate surroundings and experiences.

The Colour By Numbers webcam livestream
The Colour By Numbers webcam livestream

In this day and age, where life in the city often equates not knowing one’s next-door neighbors, this art installation helps people to feel ‘connected’ to their local environment. It demonstrates how complex digital technologies can encourage grown-ups to play using simple, yet effective means. Colour By Numbers also encourages residents to reclaim public space; anyone can leave their mark on the skyline, at least until the next person’s turn, and the whole experience is free of charge in a space usually restricted to high-paying advertisers.

All images, incl. header, by Colour By Numbers
Text by Robert Prideaux