Critical infrastructures encompass various sectors such as energy resources, manufacturing and governmental services, which tend to be dispersed over large geographic areas. With recent technological advancements over the last decade, they have developed to be increasingly dependent on Information and Communication Technology (ICT); where control systems and the use of sensor equipment help facilitate operation. In order to sustain the ever-increasing demands, it is essential that these systems can adapt by integrating various new and existing digital technologies. However, this results in an increased vulnerability to cyber-threats. In addition, the persistently evolving global state of ICT has resulted in the emergence of sophisticated cyber-threats. As dependence upon critical infrastructure systems continues to increase, so too does the urgency with which these systems need to be adequately protected. Unfortunately, the consequences of a successful cyber-attack can be dire, potentially resulting in the loss of life or a devastating effect on the operation of government services and the economy. Despite the seriousness of this problem, the development of new and innovative cyber-security methods are being hampered by the lack of access to real-world data for training, research and testing new design methodologies. As such, the project presented in this paper highlights an in-progress project, funded by UKAIS, for the development of an easily-replicable and affordable critical infrastructure testbed for cyber-security training and research.