In Venice, the paved area in the middle of a cluster of houses was known as a campo. Venice has only one square, and that is the Piazzo San Marco, the monumental gathering place before the St. Mark's Basilica, the Clock Tower (Torre dell'Orologio), and the Procuratie Vecchie. So a piazzo was a major decorative and political feature, while more modest campos were found throughout the islands and neighborhoods. And most campos were equipped with a cistern to trap and save rainwater. The cistern consisted of a brick-lined chamber filled with sand. Rain water filtered down through the sand to maintain purity.
|Campo Realto Novo, Venice|
|Calle del Teatro, Venice.|
|Palazzo Cavalli-Franchetti, Venice.|
|Campo S.Vio, Venice.|
|Calle del'Abazia, Venice.|
|Giudecca canal, Venice.|
For more information on Venetian cisterns, see these volumes on architecture:
McGregor, J. H. S. 2006. Venice from the Ground Up. Belknap Press of Harvard University Press, Cambridge, MA, 384 p.
Howard, D., and Moretti, L. 2002. The Architectural History of Venice. Yale University Press, New Haven, CT, 384 p.
Venipedia has a description of the cisterns: http://www.venipedia.org/wiki/index.php?title=Wellhead , accessed September 20, 2013.
Photographs taken with a Nexus 4 phone (sorry, no real camera this trip).