Chicago's Sears Tower marked Earth Day by shutting off the lights to its antennae.
Sears joined New York's Empire State Building and the Space Need in Seattle in the program, which was coordinated by children's network Nickelodeon.
The network asked kids across the country to turn off lights in their homes in a symbolic gesture of environmental consciousness while the landmarks did the same.
"Power Down" is part of Nickelodeon's ongoing Big Green Help environmental campaign, which is designed to empower kids to take action on the environment and connect them to energy saving and earth-friendly activities in their everyday lives.
The Sears Tower also participated in Earth Hour on March 28, in which millions of people in over 4,000 towns shut off their lights to raise awareness of global warming.
