Slieve Rushen is a mountain which straddles the border between County Cavan in the Republic of Ireland and County Fermanagh in Northern Ireland. It is also called Slieve Russell or Ligavegra (Also Legavagra, Ligavagra). It has an elevation of 404 metres above sea-level. OS 1/50k Mapsheet: 27A & 26. Grid Ref: H234 226. The mountain is made up of grey limestone with a cap of sandstone and shales and is extensively quarried by local companies. The surface is mostly covered with peat, pine forests and grazing fields. The mountain contains several caves and swallow-holes including Pollnagollum and Tory Hole which are a popular destination for potholers.