Blau began her teaching career in the Art and Art History Department at Wesleyan University. She was the Head of the Department of Exhibitions and Publications (1984-1991) then Curator of Exhibitions and Publications (1991-2001) at the Canadian Centre for Architecture.
She was a Professor of the History of Architecture (2004-2011) in the Department of Architecture at the Harvard UniversityGraduate School of Design, while Toshiko Mori was chair. Blau served as Director of the Master in Architecture Degree Programs (2008-2011). She has been part of the school's Department of Urban Planning and Design as Professor of the History and Theory of Urban Form and Design. In 2019, Blau was appointed as Director of Research by Mohsen Mostafavi.
Photographs attributed to Blau appear in the collection of the Conway Library at the Courtauld Institute of Art. Images captured includes religious and secular buildings, sculptures, and various communities.[6] A linked exhibition of her work ran there from October 2017 to March 2018, which highlighted the architectural importance of the Greystone buildings in Montreal.[7]