By the most of the lyrics I think that it's about destroying a relation between two people (friends, lovers..) so by saying "your bridges are burning" it means that the bond that connects the two is disappearing, and "gathering the ashes" means that one of them is trying to save that relationship but it's not working so he says "everything is thrown away". And now returning to the begining "these are my famous last words" probably means that these words are the last thing someone would say to his partner before breaking up. Anyways that's just my interpretation of the song, btw it's the best opener.
By the most of the lyrics I think that it's about destroying a relation between two people (friends, lovers..) so by saying "your bridges are burning" it means that the bond that connects the two is disappearing, and "gathering the ashes" means that one of them is trying to save that relationship but it's not working so he says "everything is thrown away". And now returning to the begining "these are my famous last words" probably means that these words are the last thing someone would say to his partner before breaking up. Anyways that's just my interpretation of the song, btw it's the best opener.