Hillside Elementary School as Lancaster's School
The room behind the giant windows was used in the penultimate scene as Lancaster's school office.
The Master Filming Locations
The Master was filmed in Vallejo & Oakland in the United States of America.
Building 69 (Mare Island Naval Shipyard) as Hiring Hall
Freddie Quell looks for a job.
Source: The New York Times
Admiral's Mansion (Mare Island Naval Shipyard) as Helen Sullivan's House
Lancaster Dodd and family stay at Helen's house while in Philadelphia.