Metrical Feet Setting
Quite literally, the setting of this poem is a letter, which is to say the words on the page are contained in a note from Coleridge to his son. But of course a letter isn't exactly a place, now is it?
The only other clues we get are the mention of Derwent, which refers to both Coleridge's son and a nearby river, and Skiddaw, which is a famous mountain in the Lake District in England. So when you read this poem, imagine a young Derwent Coleridge sitting in his house in Keswick, opening a precious letter from his absent father, and memorizing these lines.