Capricci
By Canalettos day there was an established tradition of fanciful views of cities, known as capricci. These could place existing buildings in new contexts, exaggerate perspectives to an absurd degree, or invent all aspects of an entirely imaginary scene.
As a youth Canaletto had trained with his father, a successful painter of stage scenery, and he would have learned the principles of perspective and how to construct convincingly an imaginary building. However the capricci emerged as an important category of Canalettos art in the later 1730s, and he may have been trying to broaden his appeal to customers who desired more overt invention in their paintings. Canalettos nephew, Bernardo Bellotto, was probably training in his studio at this time, and some of the drawn capricci may have been conceived as exercises for the young artist to copy.