A modular and hierarchical DNA assembly platform for synthetic biology is described. This enabling technology, termed MIDAS (for Modular Idempotent DNA Assembly System), can precisely assemble multiple DNA fragments in a single reaction using a standardised assembly design. It can be used to build genes from libraries of sequence-verified, reusable parts and to assemble multiple genes in a single vector. We describe the design and use of MIDAS, and its application in the reconstruction of the metabolic pathway for production of paspaline, a key intermediate in the biosynthesis of a range of indole diterpenes—a class of economically important secondary metabolites produced by several species of filamentous fungi.