Mayor Rob Ford and federal and provincial government representatives were on hand Tuesday afternoon to raise an official Toronto 2015 flag.
Manitoulin Aboriginal drummers signalled the beginning of the afternoon city hall ceremony that featured sports demonstrations and performances from Canadian artists such as Kardinal Offishall.
"Today is a special day," Ford said. "We are only three years away from the beginning of the 2015 Games. Toronto is proud — very, very proud — to host these games, and today's event, that is just the beginning of what we have to display to the rest of the world."
The countdown celebrations also included the unveiling of two month-long city-wide cultural projects.
More than 40 pianos painted by participating Pan Am countries have been placed throughout the downtown core for public use, and a photo exhibit at city hall will illustrate the experiences of new Canadian citizens.
The artistic projects are meant to engage the public in an overlooked aspect of the Games, said Ian Troop, chief executive of the To2015 committee.
"From the very beginning, when the bid to host the 2015 Games was first envisioned, it was very clear that Toronto 2015 was going to be about more than sports and athletic achievement," Troop said in a statement.
"The common thread uniting our cultural programs and events is that they are accessible to everyone. These are the People's Games," Troop said. "They will involve and engage our diverse population, and enable them to tell their own stories."
The ceremony was briefly interrupted by a group of doctors protesting recently enacted federal cuts to refugee health care.
Physicians from a local hospital began heckling Bal Gosal, federal minister of state for sport, during his remarks.
Dr. Gary Bloch, a family physician with St. Michael's hospital, said doctors are already seeing negative consequences from the cuts that took effect on June 30.
"Our patients are being denied access to medication, laboratory services, diagnostic imaging like X-rays, and in some cases are actually being denied the ability to see physicians," Bloch said.
"This is a battle we will not stop fighting."
The Pan Am Games, featuring 10,000 athletes from the 41 members of the Pan American Sports Organization, will take place from July 10 to 26 in cities across southern Ontario. The Para-Pan Am games will take place from Aug. 7 to 14.