The increasing availability of data and new ways to leverage it have pushed engineering domains into investigating a Digital Twin (DT) paradigm, which assumes full integration and cohesion between the physical and the virtual worlds. Although the prospects of digital twinning have been gradually explored within the fields of cyber-physical systems (CPS) and various BIM uses, the next level of integration needs to consider available methods and tools (procedures and technologies) which would give a digital twin more cohesion over the managed information, more adaptability and bring out more value from our virtual models. Within this chapter, we introduce the recent relevant aspects related to digital twin in research, along with existing initiatives and potential future paths. These are presented through the lenses of various application domains within the built environment by looking at digital twin requirements, technologies, architectures, modularity of services, as well as the role of semantics in achieving communication between different entities. Although the future of the digital twin paradigm remains uncertain, the vision of being able to monitor, simulate, optimise and then consequently automate and actuate the real world at various levels remains one of the most valuable prospects for our built environment, thus ensuring lower negative effects on the environment in the long-run.