On 25 October 1964, a devastating flood of the River Sava struck Zagreb, Socialist Republic of Croatia, Socialist Federal Republic of Yugoslavia (today the capital of Croatia). High rainfall upriver caused rivers and streams in the Sava catchment basin to swell and spill over their banks in many places throughout Slovenia and northern Croatia. The worst of the flooding occurred in Zagreb. Sava floods were a known hazard in the city, having affected the development of the area since the Roman times, and the 1964 flood did not have the largest extent. However, it occurred following several decades of large-scale industrialisation and urban growth which had caused the city to expand into the most flood-vulnerable areas. The quality of building construction and flood defences in the floodplain