First Croatian oil factory in Zagreb was founded in 1916. Its founder Samuel David Aleksander together with its cofounders established the first factory in Palmotićeva street; later in 1920. they planned and build a new, much larger factory in Branimirova street. From 1920. until the end of the Socialist Federal Republic of Yugoslavia, Oil factory Zagreb operated under the same address on Branimirova street, until its final move to a modern production plant on Žitnjak. New urbanistic planning and building which occurred in the late 20th and early 21st century on the site of the Oil factory Zagreb in Branimirova street brought a number of drastic changes – the demolition of the old factory buildings, building a new highway and subsequently transformation of the entire neighbourhood block. In the processes of the building of new and the destruction of old and abandoned, only a few structures remained. This thesis aims to present a historical overview of the Oil Factory site in Branimirova, its surviving edifices as well as its architectural description and a conservation study. The building which housed the boiler room and the engine room and the building which stored the water supply are the only two surviving edifices. Together they make a historic industrial whole, carry symbolic meaning and are of a great historical importance for the city of Zagreb and its industrial past. Because of the uncertainty of their destiny and a great need for their preservation, this thesis aims to establish clear arguments and methods for their protection and care. This thesis was written in the hopes that the last two remaining buildings of the once great factory site will receive proper care, adaptation and conservation following the guidelines and policies set by the licensed conservator. Hopefully, the remaining buildings would, by the end of the future adaptations and repurposing, become a place of memory and education, with their architectural and locational potential fully realized.