Macintosh Quadra 700 (1991)
The Macintosh Quadra 700 was introduced along with the Quadra 900 in October 1991 as Apple's first computers to use the Motorola 68040 processor, as well as the first to feature built-in Ethernet networking as many Unix workstations did. This is one of Apple's first two minitowers, along with the Quadra 900 of the same date. The Quadra 700 case was the same form-factor as the popular Macintosh IIcx and Macintosh IIci models, allowing users to easily upgrade to the more powerful computer. Users sometimes placed the older case vertically in a minitower orientation and the Quadra 700 recognized this by having the Apple logo and model name printed in the vertical orientation. It remains the only Mac to be "officially" convertible between desktop and tower orientations.
via Wikipedia: http://en.wikipedia.org/wiki/Macintosh_Quadra_700