Crystal Bucephalus

 was part restaurant, part time machine that took its diners to famous events in history.

The time machine was designed and built by Alexhendri Lassiter and it projected its diners through time. Turlough and the Fifth Doctor once visited it. By lowering the diner's reality quotient, they could be sent into the past to eat at fine restaurants without causing alterations in history. (PROSE: The Crystal Bucephalus)