The vacant Cavalier Motel was set on fire on June 25 and police continue to investigate.
A man torched a police cruiser and then celebrated before getting arrested, investigators said.
The American flag has been replaced, but the portable bathrooms have not been cleaned up.
Officials are investigating two suspicious fires started in Falmouth early Monday morning.
Investigators believe a person using a torch to take piping in old City Hall started an overnight Quincy fire.
A young man and two teenagers have been charged with setting a fire that destroyed two homes and damaged eight others in Beverly late Sunday night.
A man was arrested for allegedly trying to burn down the Masonic Temple Lodge on Tremont Street in Boston.
Two Massachusetts men have been sentenced in some of a string of fires set south of Boston in 2012 and 2013.
Fire officials on the South Shore are furious over a plea deal being offered to two men charged in a series of arson fires.
Boston College says a student has confessed to setting three fires on campus.