The title refers to Lord Byron's immense epic poem Childe Harold's Pilgrimage (Childe is an archaic title for the son of a nobleman). Childe Harold, after a youth spent in complete dissipation, repents his sins and leaves England on a long pilgrimage. He finally arrives in Italy where he is captivated by its combination of beauty and decay. For Byron, the remnants of Italy's great classical past made a profoundly poignant statement in a land which, at this point in its history, had lost both liberty and integrity, but was still exquisitely lovely. Turner clearly shared this feeling; when he exhibited the picture at the Royal Academy Summer Exhibition in 1832, he attached to it, printed in the catalogue, lines from the section of the poem where Childe Harold broods on Italy: '... and now, fair Italy!! Thou art the garden of the world ... / Thy wreck a glory, and thy ruin graced / With an immaculate charm which cannot be defaced'.
The figure in the foreground, in what looks like a monk's habit, is presumably Childe Harold.
Simon Wilson, Tate Gallery: An Illustrated Companion, Tate Gallery, London, revised edition 1991, p.57