We all know January 1, 2000 is not the millenium. Otherwise we'd have to have a year 0.
I have decided there are two milleniums: a colloquial millenium that the advertisers are hyping, and a mathematical millenium that happens next year.
However, an Odometer roll, coupled with the Y2K bug and FBI reports, makes it worth a party.
The last 1000 years will be celebrated with historical and artistic achievements around the globe being the focus.