Balloon borne instruments offer opportunities for astronomical observation in an environment that is superior to many ground observatories and less expensive than space borne observatories. BLAST is an infrared astronomical telescope that will use a high altitude balloon as an observation platform. The BLAST telescope has a unique set of requirements: lightweight, low cost, zenith to horizon pointing, 10 arc-second pointing accuracy, high Strehl ratio far infrared/sub-milllimeter observation. The design of the BLAST telescope takes advantage of a pre-existing 2-m experimental lightweight carbon fiber mirror. Using this spherical primary, an aspheric secondary was designed to produce a diffraction limited telescope at 250 microns. The telescope metering structure was designed and fabricated using high stiffness, low mass, thermally stable carbon fiber. The secondary mirror was aggressively lightweighted and fabricated using state of the art diamond turning technology. Design was verified prior to manufacturing using finite element structural analyses in order to demonstrate compliance with the deflection requirements of the secondary mirror when pointing zenith and near horizon. This paper will review the optical and opto-mechanical design, fabrication, integration and alignment of the BLAST telescope.