Callery pear trees in Pittsburgh. The smell of the invasive trees has been compared to rotting fish and other stinky things. Luke H. Gordon/Flickr hide caption

itoggle caption Luke H. Gordon/Flickr

Freedom House paramedics, who first were deployed in the 1960s, provided a crucial service for Pittsburgh residents. The program became a national model for emergency medical transport and care. Courtesy of University of Pittsburgh hide caption

itoggle caption Courtesy of University of Pittsburgh

At the Pittsburgh International Airport, Consol Energy will begin extracting gas — even under the runways. MeRyan/Wikimedia Commons hide caption

itoggle caption MeRyan/Wikimedia Commons

The headquarters for University of Pittsburgh Medical Center and Highmark Blue Cross/Blue Shield dominate the Pittsburgh skyline much as they organizations have dominated health care in the region for decades. Jeff Brady/NPR hide caption

itoggle caption Jeff Brady/NPR

A security guard closes the gate at the Pittsburgh Zoo, where a 2-year-old boy was killed Sunday. John Heller/AP hide caption

itoggle caption John Heller/AP