As Cecilia Powell first identified, this sketch represents part of a view of the Bay of Baiae seen from near the so-called of Temple of Mercury, a domed bath-house which is part of the ruins of a large Roman spa complex.1 The vista looks south-east across the bay towards the Posillipo coastline and the distant island of Nisida, whilst in the middle distance on the right is the Castello di Baia (Castle of Baiae). The composition spills over onto the opposite sheet of the double-page spread, see folio 79 verso (D15712; Turner Bequest CLXXXIV 77a). In the bottom right-hand corner of the page is part of a related study of the ruins.
Turner made a large number of sketches of Baiae and its ancient monuments, see folios 79 verso, 80 verso–81, 82, 84 verso–89 verso, 92 (D15712, D15714–D15715, D15717, D15722–D15732 and D15737; Turner Bequest CLXXXIV 77a, 78a–79, 80, 82a–87a and 90). These drawings formed the compositional basis of one of three oil paintings completed in the months and years following Turner’s return from his first tour of Italy, The Bay of Baiae, with Apollo and the Sibyl exhibited 1823 (Tate, N00505).2 Indeed the finished picture features a vista very similar to that depicted here and repeated within other on-the-spot drawings, and it is therefore possible that the artist was already planning the composition during his visit to the area.3