Year 66 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Lepidus and Tullus (or, less frequently, year 688 Ab urbe condita). The denomination 66 BC for this year has been used since the early medieval period, when the Anno Dominicalendar era became the prevalent method in Europe for naming years.
Tigranes II is forced to surrender, by a payment of 6,000 talents, and is reinstated by Pompey as a "friend of the Roman people" to hold Armenia as a buffer zone.
After his triumph in 66 BC, Lucullus diverted an entire mountain stream to fill the fishponds of his Neapolitan estate and constructed additional ones near Baiae.