Watch TV Series Celtics City HBO Online Free. Celtics City chronicles the history, cultural impact, and extraordinary tale of the NBA’s winningest and most storied franchise, the Boston Celtics, the current 2024 NBA Champion. The series contains extensive, never-before-seen archives and more than 80 interviews of past and present Boston Celtics legends – from Bob Cousy and Larry Bird to Jayson Tatum and Jaylen Brown.