AboveNet was a provider of high bandwidth telecommunication circuits primarily for large corporate enterprises and communications carriers in 17 markets in the United States and 4 markets in Europe. Its private optical network delivered key network and IP services and was used in financial and legal services, media, health care, retail, and government.

The company was formerly named Metromedia Fiber Network and changed its name to AboveNet in 2003 after emerging from bankruptcy.

Before its bankruptcy in 2002, the company was financially backed by John Kluge and Verizon.

In 2012, the company was acquired by Zayo Group for $2.2 billion in cash.

The company was founded in 1993 as AboveNet, by founder Sherman Tuan. It initially focused on 'one-hop' internet connectivity and providing dark fiber to communications carrier customers in the U.S. and Europe.

Abovenet Communications became a public company via an initial public offering in December 1998 and soared 32% in one day in March 1999 during the dot-com bubble after announcing a stock split.

In June 1999, Metromedia acquired Abovenet Communications, including its subsidiary PAIX, an operator of Internet peering exchanges. Following the acquisition, the company changed its name to Metromedia Fiber Network in 2000.

In 2000, the company acquired M.I.B.H., a networking consultancy operated by Paul Vixie, for $51 million in cash and stock.