Phillips's victory marked a turning point in Toronto history and its transformation from a Protestant, staunchly British and conservative city to a modern multicultural metropolis.

On 23 March 1959 Phillips welcomed exiled King Peter II of Yugoslavia on an official tour to City Hall but forgot about the Serbian Orthodox Bishop from the Diocese of Chicago that he left waiting in the council chambers.

Large blocks of downtown were purchased and razed and many landmark buildings and neighbourhoods were destroyed such as the University Avenue Armouries, the Chorley Park estate, the General Post Office (built in 1873 in the Second Empire style, and the most expensive federal building ever constructed in Canada), Toronto's original Jewish community (called the Ward) around Old City Hall, and Toronto's Old Chinatown.

Old City Hall itself narrowly escaped being demolished and Fort York survived a council vote to be moved to Coronation Park after the Toronto Historical Association rallied public support.

Nathan Phillips is best remembered as the driving force behind the construction of Toronto's New City Hall and the selection of a striking avant-garde design by Finnish architect Viljo Revell.

[12] Before a crowd of 500, on his 69th birthday, he broke the ceremonial first sod and hit a button that detonated some explosives to signal the start of construction on the new square and City Hall.

[13] When mayor Phil Givens opened the square's skating rink on 29 November 1964, Phillips was there at the ceremony and practicing his photography hobby as well.