It’s Tuesday, November 6th. Nobody knows what caused a Main Line mansion to explode Sunday night. But when the vacant 6-bedroom house exploded, thousands heard a loud boom, and many called 9-1-1. In nearby homes, residents reported broken windows and blown-in doors. Thankfully, no one was hurt in the blast. Neighbors said the Gladwyne estate had been undergoing renovations for years. It could take weeks for authorities to find out exactly what happened.