Winnipeg Arena, which stood on the north end of the mall site, predated the shopping hub by 4 years. It served as the home venue for the Winnipeg Warriors, Winnipeg Jets and Winnipeg Monarchs hockey franchises.
Photo from Wikipedia / "JETStender"

A mid-1960s view of the south end of POLO PARK CENTRE. The open-air complex had been enclosed and heated in 1963-1964.
Photo from University of Manitoba, Winnipeg Building Index

By 1969, the 2 supermarkets on the north end of POLO PARK had been relocated to the east side of the centre. The original stores were sectioned into inline retail spaces. An Eaton's department store was also built. The mall now housed over 60 stores and services.