The city is planning a reopening ceremony on Sept. 21 to mark the completion of renovations to the Saltonstall School. The event will be held at 10 a.m. at the school, 211 Lafayette St. The public is invited to tour the building immediately after the ceremony. The kindergarten to Grade 8 school was closed for two school years for the renovations, with its students relocated temporarily to the Federal Street and Bentley schools. The Saltonstall will reopen when the new school year begins on Sept. 4. The renovations included replacement of the roof, boilers, and lighting system; repairs to the exterior brickwork; replacement of the windows in the original section of the building; replacement of the telecommunications system; new linoleum floors; and the addition of air conditioning. The Massachusetts School Building Authority provided 78 percent reimbursement for the project’s approximately $13.5 million cost. The School Building Authority is also providing 78 percent reimbursement for a similar repair project at the Collins Middle School that is set for completion next January.