My forest celebrated the ten-year anniversary of the initial promotion today. We had upgraded from an NT4 multi-master configuration, so this was a new promotion to become the empty root. The account domains were slowly upgraded over the next year. Technically, the domain services as a whole are more than 10 years old, but the official NT4 dates are lost to the sands of time.
c:\>adfind -config -f name="Enterprise Configuration" whencreated -alldc
AdFind V01.40.00cpp Joe Richards (email@example.com) February 2009
Using server: xxxx.xxxx.com:389
Directory: Windows Server 2003
Base DN: CN=Configuration,DC=xxxx,DC=com
>whenCreated: 2000/04/12-19:25:22 Eastern Daylight Time
1 Objects returned
We held a party for it today, and even got a “PromoDay” cake.
 Not technically “my forest”. It does belong to the widget company for which I work, and I didn’t even work for them 10 years ago, and had nothing to do with its creation. joe was responsible for most of it . These days there are 5 EAs with operational responsibility, and me with engineering responsibility who can likely continue to call it “ours”.
 There are a lot of good stories about the early days of our AD. This event brought out a few of them from ensuring joe didn’t promote the forest as joe.com to the buddy builds that were delivered almost daily as we pushed the scalability limits of Windows 2000 beyond what Microsoft had yet seen, but they’re joe’s to tell, not mine. Go read about them if you want.