Heidelberg is an ancient university town with a fine castle, on the River Neckar, a picturesque tributary of the Rhine. Turner visited on three occasions: in 1833, 1840 and 1844. This is one of the finest of all the artist’s late works. Here he has moved far beyond a concern for topographical accuracy and created a glowing, almost hallucinatory image. The watercolour is also distinguished by its size; it is one of the largest of the Vaughan Turners in Edinburgh and was probably always meant to be an exhibition piece.