The aim of the present research is to analyze a fire that happened in Zadar within the old city nucleus, on the peninsula, where one of the most complex Zadar Public Fire Brigade interventions on a residential and commercial building took place. It had to be established why the fire had spread so quickly over most of the building. The data used in the setting up of the present work are from sources of the Zadar Public Fire Brigade, Police Station and based on conversations with the relevant shareholders. The results acquired from the research indicate that the residential and commercial building where the fire took place were due to the age, construction and architectonic building solutions that go back several centuries, and predetermined the spreading of fire in case of fire outbreaks. No construction rules or fire protection rules were applied. The material used for the performance of mezzanine and roof constructions were mainly made of wood which is combustible material, and not protected from high temperatures which additionally enhanced the quick spreading of the fire. Fire sectors also did not exist and this facilitated the spreading of fire through mezzanine wooden structures to the neighboring rooms in a very short period of time. The evacuation routes which the inhabitants could use to escape did not exist in the building on fire. The fire brigade approach functioned partially considered the position of the fire outbreak when speaking of the old buildings on the peninsula. On the basis of the present research, it can be concluded that the other buildings in the mentioned part of the city are in a potentially dangerous situation if the consciousness of the citizens does not change. In the reconstruction and even adaptation of single apartments measures of fire protection and construction regulations should definitely be adhered to, which are in any case a more expensive solution but in the end save lives and property. This refers to fire alarm, inner hydrant network and the construction of stable systems of fire extinction which would significantly slow down the spreading of the fire until the arrival of the fire brigade.. It is necessary for the firefighting approaches to be adequately marked with pertaining signs and to be regularly controlled whereby the firefighters could have unhindered access as close as possible to the building on fire but these are mostly inaccessible in single parts of the peninsula.