How far back in time can you trace your family tree?

Question:

How far back in time can you trace your family tree?

My oldest known ancestor was mayor of a city in Germany in the 1600's.

Best Answer - Chosen by Asker: On www.familysearch.org I was able to trace one line of my family back to about 30 BC or so. It was a line from European royalty so I must assume that it's somewhat accurate. I urge anyone who hasn't tried this site to give it a whirl, it's run by the Mormons and it's free. I mean completely and utterly free - no registration, no pop up ads, no spam - free. I found a lot of information on my family tree that I had no idea existed.