Red Gap

Red Gap is a hill around 400 feet above sea level, 16 kilometres southwest of Dublin city centre in the Dublin Mountains at Saggart. It is also known as Saggart Hill or Slieve Thoul. Today, Red Gap is home to farmland and telecommunication masts. The hill has FM radio transmitters for Newstalk, Kfm, LMFM, i105-107 and East Coast FM.
The hill is also home to low-power fill in transmitters of Nova 100 and 4FM, designed to cover the Dublin commuter belt
The old-time song "Campbell's farewell to Red Gap" is believed to be referring to this hill.