Located between King and William streets, Winfield Square extended north from Flinders Lane. The name referred to the nearby Winfield Building, formerly the Wool Exchange (487-495 Collins Street), erected in 1891. On the other side of the lane was the Rialto Building (497-503 Collins Street), built in the same year. The façades of both buildings remain standing today as evidence of the late Victorian boom period architecture. Although Winfield Square no longer exists as a laneway, its original bluestone cobbled paving survives intact and can be seen on the ground floor atrium of the Rialto Building.
In 1894, the lane was also known as Rialto Lane, as noted by W. Anderson, secretary of the Bacchus Marsh Concentrated Milk Co. whose offices were located by the Wool Exchange. Anderson wrote to the City of Melbourne complaining about the condition of the lane and reporting that 'the poultry fruit marketing that goes on here is accompanied by a lot of garbage [and] dead poultry, which the vendors deposit just outside our stores to the detriment of our sensitive productions'. In 1901, Winfield Square was home to the Neptune Oil Company and Robertson & Gardner, who were auctioneers and dairy produce salesmen.