Not on display
As recognised by Ian Warrell, the setting is Brescia, with the New Cathedral (Duomo Nuovo) and Old Cathedral (Duomo Vecchio) and the tower of the Broletto Palace.1 The viewpoint is the south-west corner of what is now the Piazza Paolo VI, with the simple Romanesque rotunda of the old cathedral on the right, dominated by the façade and drum of the Baroque new cathedral (then lacking its dome), with the slim, castellated tower of the civic Broletto Palace beyond.
In the foreground is the fountain which still stands outside the doorway of the old cathedral. Turner appears to have made a written note of the Corinthian order of the later building’s west front. The slight sketch on folio 18 recto (D14350) possibly shows Brescia; for the city in relation to Turner’s route east across northern Italy to Venice, see the sketchbook’s Introduction.
Undated notes by Ian Warrell in Tate catalogue files.