For more than a century, the re-creation of the urban realm in the sky through connections between buildings at height has been understood as having a vast potential for the enrichment of our cities. Whilst the world has seen a push towards greater height and urban density in our major urban centers, however, the ground level remains almost exclusively the sole physical plane of connection. As the world rapidly urbanizes, greater thought needs to be expended on how horizontal space can be developed at height, particularly as public space is increasingly at a premium, energy consumption remains high and concerns about the effects of density and isolation on physical and mental health take new precedence. Simultaneously, new transportation technologies such as ropeless elevators promise to overcome some of the logistical challenges that have held back 3-D urban development from its full potential.This Guide, the culmination of an 18-month research project, thanks to generous research funding by thyssenkrupp Elevator, is intended to provide a new generation of informed speculation on the future of the skybridge, in the context of the three-dimensional city vision. It is broken into seven chapters, each illustrated by vivid images and explanatory graphics. In the first half, it covers the early visionary conceptions and timeline of skybridge development to the present day, and examines 15 state-of-the-art modern skybridge projects in detail, subjecting these to qualitative and quantitative analysis. In the second half, cross-disciplinary considerations are provided for owner-developers, architects, engineers, and developers of skybridge-linked projects, citing exemplary current practices, concluding with potential future scenarios based on the latest visionary thinking and innovations.