Percy Shelley formulated "Mont Blanc" at the end of July 1816, when along with Mary Godwin and Claire Clairmont (Mary Godwin's step-sister) he toured the Chamonix Valley by Mont Blanc; Europe's highest mountain [REF].
Shelley finished a draft of the poem before September, and it was published in 1817 as part of the Shelleys' travel narrative History of a Six Weeks' Tour [REF].