When San Francisco first installed 25,000 LEDs to the San Francisco–Oakland Bay Bridge in 2013, the structure became the world's largest light sculpture. The Bay Lights ran for two years, but the lights are now back as a permanent fixture.
Illuminate the Arts, a San Francisco nonprofit, was established with the goal of bringing the installation to fruition. While the intention was to display the light show for only two years, it became so popular that the organization raised the $4 million required to make the installation permanent.
Designed by New York City–based artist Leo Villreal, The Bay Lights measures 1.8 miles wide and 500 feet high. Created for the Bridge's 75th anniversary, the display is a show of computer-generated forms that fall, rise, and swoop across the bay in patterns that never repeat. The patterns resemble the bay's surroundings, reflecting the passing traffic and boats, breaking waves, and changing weather patterns.
The 25,000 LED bulbs were hand-installed by a team of trained riggers to 300 vertical cables that stretch the width of the bridge. A cloud–based technology monitors and maintains the lighting remotely.
You can see display in this video about the installation from The New York Times (taken in 2013):
For more on the display, visit inhabitat.