When it became clear that the first municipal offices could no longer accommodate the burgeoning contingent of North York civil servants, a five-acre site was purchased on the west side of Yonge Street. The first section of the second municipal building at 5000 Yonge was ready for occupancy on March 10, 1956. Designed by Sproatt and Rolph on Modern Georgian lines, the original structure was expanded several times to make room for new departments, such as Data Processing, and offices for the members of the Board of Control.
On January 1, 1967, the Township of North York became the Borough of North York. This happened following the amalgamation of 13 area municipalities in Metropolitan Toronto down to six, including the City of Toronto, and the boroughs of North York, Scarborough, East York, York, and Etobicoke. The title of the head of council was changed from reeve to mayor, and the first mayor of the Borough of North York was Jim Service.
By the 1970s, the North York civil service had once again outgrown the space in their offices. This resulted in the construction of the third municipal building, which opened on April 3, 1978. On February 14, 1979, North York graduated from borough to city. In a happy coincidence with Valentine’s Day, council adopted the new motto “The City with Heart.” The new City Hall and offices were located in the North York Civic Centre, which by the mid-1980s would comprise civic offices, Mel Lastman Square, the North York Central Library, Douglas Snow Aquatic Centre, and North York Memorial Community Hall – all on the west side of Yonge at Park Home Avenue. In support of the vision of a new downtown in North York, the North York Centre subway station opened in 1987, providing easy access to the new commercial centre.