Geograph - photograph every grid square

Pollnagollum Cave is Ireland's longest, measuring over 16 kilometres in length. The system consists of a maze of interconnected stream passages and has proved popular with cavers and potholers. Non-cavers can walk down several flights of steps to a viewing plattform that sits opposite the main cave entrance. It's most attractive feature is a 12 metre waterfall that cascades down the limestone bluff above, before disappearing underground.
Pollnagollum Cave is part of the Marble Arch Caves Global Park.

The Marble Arch Caves Global Geopark straddles the border between Northern Ireland and the Republic of Ireland. It is centred on the Marble Arch Caves and in 2001 it became one of the first geoparks to be designated in Europe.
The Geopark features various sites which demonstrate the geological and wider natural heritage of the area, as well as the cultural heritage relating to 7,000–8,000 years of recorded human occupation since the last ice age. It is jointly managed by Fermanagh and Omagh District Council and Cavan County Council.
Wikipedia: Link

GOT was filmed in a variety of locations in Northern Ireland, as well as other countries.