View of the Gate of Cologne at Aix La Chapelle / Drawn & engraved in Aqua-Tinta by the Rev. J. Gardnor. In: Views taken on and near the river Rhine, at Aix la Chapelle, and on river Maese / by John Gardnor. Engraved in aqua tinta by William & Elizabeth Ellis. London : Ellis & Walter, 1788