When local residents and admirers learned the iconic Sycamore Gap tree in northern England had been cut down last year, they wanted to know why and who could have committed such a senseless act. On Monday, prosecutors will begin providing some of those answers. Two men are scheduled to go on trial in Newcastle Crown Court on charges related to toppling the tree and damaging a section of the ancient wall built by Emperor Hadrian in A.D. 122 to protect the northwest frontier of the Roman Empire. The tree, perched symmetrically in a dip between two hills, had been a draw for tourists and locals who marked important life events under its canopy.