Progress report on the performance of the Multiple Mirror Telescope.

A discussion of the unusual features of the Multiple Mirror Telescope (MMT), located in Tucson, Arizona, which will probably be included in future advanced technology telescopes, is presented. The MMT uses alt-azimuth mounts, and has a special optical configuration that makes it possible to make the optics support structure exceedingly rigid. The six MMT telescopes are coaligned on field stars and the coalignment system relies on the extraordinary mechanical stability of the MMT to keep the telescopes coaligned for long periods when no field stars are available. Details of the image quality of the MMT and the use of the MMT both for IR Michelson interferometry and for optical speckle interferometry, as well as of the building housing the MMT, are provided.