3XN was founded as Nielsen, Nielsen and Nielsen in Aarhus in 1986 by the architects Kim Herforth Nielsen, Lars Frank Nielsen (partner until 2002) and Hans Peter Svendler Nielsen (partner until 1992).
The partnership today consists of Founder Kim Herforth Nielsen; CEO Bo Boje Larsen who became Partner in 2003; and Head of Competition Jan Ammundsen who became Partner in 2007.
In 2007 3XN established GXN; a Research & Development department that scans the market and the latest research for pioneering ideas, focusing on green and digital architecture, new materials, technology, and working methods.