From Longman Dictionary of Contemporary Englishoffice buildingˈoffice ˌbuilding (also office block British English) noun [countable] TBBBBOa large building with many offices in it, especially ones that belong to different companies
Examples from the Corpus
office building• The fireball destroyed a prefabricated office building before setting a four-storey office block ablaze.• And the office building was next to the storage tank.• In fact, I seem to remember it was a bloody great chunk of the office building took my head off. 