Interior of the passenger liner 'Aquitania' (1914) showing the Long Gallery, between the First Class Lounge and First Class Smoking Room on the port side of the Promenade Deck (A Deck); a view from the after end.

The Long Gallery was both an art gallery and an additional lounge area with views of the sea. It was decorated in the Adam style by Waring & Gillow Ltd, London.

The Long Gallery, also called Historical Gallery, contained portraits and topographical prints. Its presence was likely to have been nurtured by the well established practice of including these spaces in country houses and grand townhouses. Long galleries made their appearance in sixteenth-century aristocratic residences and were originally intended as enclosed spaces in which exercise could be taken under cover. Such galleries contained little or no furniture, but, as the fashion for collecting portraits grew rapidly in the sixteenth century, they soon became privileged sites for the hanging of pictures. The addition of galleries remained fashionable well into the nineteenth century and, by 1850, most aristocratic houses in London had galleries exclusively devoted to the display of works of art.

The design of the interiors on the 'Aquitania' was largely the work of Arthur Joseph Davis (1878-1951) of the architects Mewès & Davis, London.