Facebook's Oldest User Is 101 And Florence Detlor has met Mark Zuckerberg By Evann Gastaldo, Newser Staff Posted Aug 28, 2012 11:43 AM CDT 7 comments Comments Sheryl Sandberg posted this photo of her and Mark Zuckerberg with Florence Detlor. (Facebook) (Newser) – If your grandmother insists she can't figure out Facebook, introduce her to Florence Detlor. At 101, she's the oldest registered user of the social networking site, Mashable reports. Facebook COO Sheryl Sandberg posted a picture of herself and Mark Zuckerberg with Detlor at the company's headquarters, which nearly 7,000 people have "liked" so far. Detlor's profile indicates she lives in the same city as Facebook HQ, Menlo Park, and that she's been a member of the site for three years.