An integrase monomer consists of three structural domains: the amino-terminal helical bundle, the core catalytic domain and the carboxy-terminal domain. Viral DNA integration into the host genome is, however, catalysed by a highly stable nucleoprotein complex called the intasome, in which four integrase monomers bridge a pair of viral DNA ends — a structure that Hare et al.1 have now solved, putting the pieces of the puzzle together. Inhibitors of HIV-1 integrase bind to the intasome rather than to free integrase, making the new structure particularly valuable.