One of Giovanni Piranesis fictional prisons; the main inspiration for Piranesis imagery. 

The Drawbridge, 1761
Giovanni Battista Piranesi, Italian, 1720–1778
Etching
plate: 54.5 x 40.7 cm. (21 7/16 x 16 in.) sheet: 64 x 49.2 cm. (25 3/16 x 19 3/8 in.) frame: 77.5 × 62.2 × 2.5 cm (30 1/2 × 24 1/2 × 1 in.)
Princeton University Art Museum. Gift of Frank Jewett Mather Jr.
x1938-13 g