While visiting the MMT (Multiple Mirror Telescope) visitors center in southern Arizona, I happened to see the observatory off in the distance with the moon rising behind it. The MMT was the observatory with the separate (6) 1.8M round mirrors from the late 1970's that got replaced in the late 1990's with the single 6.5M mirror from the local 'spin cast' mirror lab in Tucson. This change more than doubled the effective light gathering area. The telescope is still called the MMT, which is no longer an acronym.