The Maine Celtics are an American professional basketball team in the NBA G League based in Portland, Maine, and are affiliated with the Boston Celtics. The Maine Celtics play their home games at the Portland Expo Building. The team debuted in the 2009–10 season as the Maine Red Claws and have since won three division titles. The Boston Celtics purchased the franchise in July 2019 from Maine Basketball, LLC, a company chaired by William Ryan Jr., and renamed the team the Maine Celtics in 2021.

The Portland Exposition Building, also known as The Expo, is a sports and convention center building complex in Portland, Maine. The complex includes five inter-connected buildings with 24,000 square feet of exhibition space and ten meeting rooms. It is adjacent to the Hadlock Field and the Portland Ice Arena.