The lawn of the U.S. Capitol was covered in 7,000 pairs of shoes, to symbolize the 7,000 children killed by gun violence since the 2012 Newtown shooting.
The global advocacy group Avaaz planned the protest to "bring Congress face-to-face with the enormous heartbreak of gun violence" and demand change, the group said in a statement.
According to Avaaz, the 7,000 deaths estimate is based on a statistic from the Centers for Disease Control that 1,300 children die from gun violence every year.
The shoes covered more than 10,000 square feet and were donated by people across the country, including celebrities like Bette Midler, Susan Sarandon, Alyssa Milano, Chelsea Handler and Vanessa Bayer.
"It's hard when you look at the scale, over 10,000 square feet of shoes on this lawn, and you're just confronted by the consequences of not passing gun control laws," Avaaz deputy director Emma Ruby-Sachs said.
Ruby-Sachs noted an "amazing number" of people stopped by to view the memorial.
"We had school groups that were here in D.C. on tours, we had members of Congress stop by....it all led to some amazing conversations," Ruby-Sachs said.
Several members of Congress also posted about the memorial on social media.
"Congressional Republicans' inaction on common sense gun reform is outrageous," tweeted Rep. Tim Ryan, D-Ohio. "We need to keep our kids safe. We can’t let any more shoes be added."
