On April 29, 2015 MIT unveiled a permanent memorial in honor of Police Officer Sean Collier, who was killed in the line of duty on April 18, 2013. The Collier Memorial, located between the Stata Center and the Koch Institute for Integrative Cancer Research, was constructed by central collaborators J. Meejin Yoon, head of the department of architecture, and CEE Professor John Ochsendorf, along with Suffolk Construction. “It’s made of 32 stones, each weighs about 12,000 pounds on average,” Ochsendorf said. “They’re locked together in a three-dimensional jigsaw puzzle. Our goal was to show the best of MIT for Sean Collier.” More than 3,000 people attended the commemoration of the memorial. For a gallery of images from the event, please see here. To watch a documentary on the structure’s construction, please see here.