The Arcminute Microkelvin Imager is a pair of interferometer arrays operating with six frequency channels spanning 13.9-18.2GHz, for observations on angular scales of 30arcsec-10arcmin and for declinations greater than -15° the Small Array has a sensitivity of 30mJys-1/2 and the Large Array has a sensitivity of 3mJys-1/2. The telescope is aimed principally at Sunyaev-Zel'dovich imaging of clusters of galaxies. We discuss the design of the telescope and describe and explain its electronic and mechanical systems. We request that any reference to this paper cites `AMI Consortium: Zwart et al. 2008'. Issuing author: jtlz2 [at] mrao.cam.ac.uk (jtlz2[at]mrao[dot]cam[dot]ac[dot]uk) ‡ Present address: Kavli Institute for Cosmological Physics, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637, USA. § Present address: The University Chemical Laboratory, Lensfield Road, Cambridge CB2 1EW. ¶ Present address: Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain. ∥ Present address: Department of Physics, Columbia University, 538 W. 120th Street, New York, NY 10027, USA. ** Present address: Joint ALMA Office, Av El Golf 40, Piso 18, Santiago, Chile. Present address: Astrophysics Group, Department of Physics, Denys Wilkinson Building, Keble Road, Oxford OX1 3RH. ‡‡ Present address: MPI für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn, Germany. §§ Present address: Astrophysics Group, H. H. Wills Physics Laboratory, Royal Fort, Tyndall Avenue, Bristol BS8 1TL. ¶¶ Present address: UC Santa Barbara, Santa Barbara, CA 93106, USA. ∥∥ Present address: NRAO Technology Center, 1180 Boxwood Estate Road, Charlottesville, VA 22903, USA. *** Present address: Spatial Technology Ltd, 1 Quayside, Cambridge CB5 8AB.