 The porch was attached to the rear of an apartment building located in the Lincoln Park neighborhood of the city 's North Side . The second and third floors were being used as a party venue at the time of the collapse . Most of the party @-@ goers were in their early 20s , and knew each other from their days at New Trier High School and Lake Forest High School of Chicago 's North Shore suburbs . One witness says she warned other people in the building that the balconies were unsafe , but another later said that " it looked like it was newly built . It looked sturdy . " 
