Marianna started her career at the Free State Museum Services in 1982 and since 1987, has been a Researcher and Cultural Historian in the Department of History at the Museum.
She obtained the degrees BA (1980), BA Hons. (1982) and MA (Cultural History) (1993), as well as a Postgraduate Diploma in Museology (1981) at the University of Pretoria. She completed her PhD in History at the University of the Free State in 2014 and was awarded The Protea Boekhuis prize by the Suid-Afrikaanse Akademie vir Wetenskap en Kuns in 2015 for her thesis Bloemfontein gedurende die bewind van president F.W. Reitz, 1889-1895: n kultuurhistoriese studie, for the best doctoral thesis (History) in Afrikaans.
She concentrates on research on the architectural and cultural heritage of Bloemfontein and the Free State and is involved in the conservation of building structures and heritage sites in Bloemfontein and the Free State. She has published many articles in scientific journals, magazines and newspapers and is co-author of two books about the architecture of the Free Sate namely Boukunsskatte van die Vrystaat and Vrystaatse argitektuur – Histories-argitektoniese ontwikkeling van die Vrystaatse boukuns: n oorsig. She also serves as Council Member of Heritage Free State (the Provincial Heritage Resources Agency or PHRA).