Time-travel is so cliché

In the midst of wizarding war, and with the muggle WWIII (year 2013) looming on the horizon, 25 year old Harry is struck by a stray curse and sent back in time... This is the story of how Hogwarts rose from the ground and from the friendship of four extraordinary people. Anyway, this is no slash, though there might be some HP(SS)/RR later on.