Diagrids are load-bearing structures made of steel diagonal grids. They were first used in the great buildings of the turn of the millennium, such as the Swiss Re Tower in London ("e;The Gherkin"e;) and the Hearst Magazine Tower in New York City. Dagrids owe their ensuing popularity not only to their stunning aesthetic value, but also to their very tangible benefits: lateral loading capacity, a massive saving of material, a significant gain in open, usable floor area, and increased flexibility. At its opening in 2014, the Leadenhall Building in London will be the first skyscraper without a bearing inner core-thanks to a diagrid structure.This book explains comprehensively for the first time all of the aspects involved in this new bearing structure. The author, experienced in teaching, research, and practice (recent publication: Understanding Steel Design. An Architectural Design Manual, 2011), has tracked the development of this technology from its beginnings and employs photographic documentation of the construction phases of many diagrid structures.