For Piazza San Marco:

I have reverted the last three alterations for the following reasons:

Removal of spaces and headings under References: In my opinion the extra spaces improve the laytout of the article. The headings also were completely harmless and in my view desirable. Removing them does no good.

The removal of the preamble to the History section is pointless. It explains the division of the section and the next sentence is more meaningful if it is included. The removal of the dates seems inexplicable to me; many readers will find them useful.

The alteration in the headings is also inexplicable. They were put in for a purpose. The sections are 'Descriptions' as opposed to History. One is a description of the Piazza, the other of the Piazzetta, which is exactly what the headings said.

References

Honour, Hugh: The Companion Guide to Venice (2nd edition. London. 1977)

Lorenzetti, Giulio: Venice and its Lagoon (1926. 2nd edn 1956) translated by John Guthrie (Lint, Trieste. 1975)

Howard, Deborah: The Architectural History of Venice (Yale University Press. 2nd revised & enlarged edition. 2002)

Norwich, John Julius: A History of Venice (Penguin Books, 1 vol edition, 1983)

Perocco, Guido & Antonio Salvadori: Civiltà di Venezia. Vol.2: Il Rinascimento. (3rd edition, revised and corrected. Venice. 1987)

Sansovino, Francesco: Venetia Città Nobilissima. (Venice. Original edition 1581. Edition of 1663 with additions by Martinioni reprinted in facsimile - Gregg International Publishers Ltd, 1968)

Sanudo Diary = Venice Cità Excelentissima - Selections from the Renaissance Diaries of Marin Sanudo. ed: Patricia H.Labalme & Laura Sanguineri White (Johns Hopkins University Press, Baltimore. 2008)

Tassini, Giuseppe: Curiosità Veneziane (9th edition, 1988)