Computing History | Haus des Lehrers — Project Blinkenlights Made the City Interactive

On September 11, 2001, the Chaos Computer Club switched on Project Blinkenlights at Haus des Lehrers beside Berlin's Alexanderplatz. A [contemporaneous WIRED report](https://www.wired.com/2001/12/hackers-show-light-in-a-new-art/) later quoted project lead Tim Pritlove confirming that start date, when the day's global events understandably left the installation almost unnoticed.

The display was an 18-by-8 grid built from the building itself. One lamp occupied each of 144 rooms across the upper eight floors, while networked controllers and a central computer turned the windows into monochrome pixels.

Blinkenlights did more than play fixed sequences. People could create small animations for display, send graphic messages called Loveletters, or telephone the system and use a mobile keypad to play Pong on the facade, with the city street becoming both audience and interface.

That low resolution was part of the experiment's force. The [Chaos Computer Club's retrospective](https://media.ccc.de/v/camp2023-57001-project_blinkenlights) calls it a simple but impressive interactive installation and records how the 144-window matrix led to larger successor projects in Paris and Toronto.

WIRED reported that the club was receiving submissions from several countries and about 10,000 website visits a day by December, figures attributed to the CCC rather than independently audited. Even at 18 by 8 pixels, participants could recognize letters, icons, a bouncing ball, and the logic of a computer display written across an occupied city building.

The event belongs to hacker history because it made a normally hidden computing stack public: software, controllers, lamps, telephone input, and human participation all became legible at architectural scale. It also showed a civic side of hacker culture—curious, playful, collaborative, and willing to treat urban infrastructure as a medium rather than a target.

The pin marks the actual installation site, Haus des Lehrers at Alexanderstrasse 9, not a later CCC office or an approximate Berlin center. The surviving high-rise still faces Alexanderplatz, and the [project's mapped record](https://commons.wikimedia.org/wiki/Category:Project_Blinkenlights) places the illuminated facade at 52.521361, 13.416278.

Photo: Tim Pritlove, CC BY-SA 3.0, via [Wikimedia Commons](https://commons.wikimedia.org/wiki/File:Project-blinkenlights-aerial-view.jpg).