Here is the schedule as posted by the Celtics:
As they have in recent past, the preseason games will be against division rivals: Nets, Knicks, and Sixers. This season they won't be playing the Raptors as they did in the past couple of seasons, but will open their preseason in Europe against Olimpia Milano and Real Madrid.
The training camp in Europe is good for two things. One, the Celtics begin earlier than they would if they were starting training camp in the US as they normally do. And, second, as Doc was always saying, being away from everything with just the team together, they will gain added chemistry as a team.