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An Ancient Port:Squaring
An Ancient Port:Squaring
After squaring an original design with black chalk lines, an artist could then easily transfer a design square-by-square to another surface. In this case, Piranesi used these lines to shift his preparatory design to an etching plate.

Giovanni Battista Piranesi
Italian, 1749 - 1750
Red and black chalk and brown and reddish wash, squared in black chalk
15 1/8 x 20 13/16 in.