The basic principles underlying the fabrication, at the <br />
Arizona Mirror Lab, of large lightweight honeycomb mirrors for <br />
ground--based telescopes will be described in the context of the MMT <br />
conversion and the Magellan project. The current status of the Large <br />
Binocular Telescope project will then be reviewed and will be <br />
followed by a discussion of the 21m Giant Magellan Telescope project, <br />
the San Pedro Martir Twin telescopes and the Large Synoptic Survey Telescope.<br />