Montpelier Hill, Mountain summit in County Dublin, Ireland

Montpelier Hill is a 383-meter (1257-foot) summit on the northern section of the ridge encircling Glenasmole valley in County Dublin. Stone ruins stand at the highest point and overlook gentle slopes and moorland in all directions.

William Conolly, Speaker of the Irish House of Commons, built a hunting lodge here around 1725, using stones from a prehistoric passage tomb on the summit. After a storm blew off its slate roof, he replaced it with an arched stone roof. The Dublin Hellfire Club met in the building between 1735 and 1741, and it was later nicknamed the Hell Fire Club.

The hill's English name comes from Mount Pelier House, a ruined Anglo-Irish country house on its northern slope; the Irish name Slieve Gorra is also used. The Hell Fire Club name passed to the forestry plantation on the slopes, Hell Fire Wood, planted with Sitka spruce, larch and beech. Behind the lodge, a circular mound about 15 metres across marks the passage grave whose stones were reused in the building.

The hiking trails begin at the parking area along road R115 and lead through open moorland up to the summit. The ascent takes about one hour and follows partly rocky paths that can become slippery when wet.

The roof was replaced with an arched stone roof built like a bridge, which survived tar barrels set alight during Queen Victoria's 1849 visit. A fallen standing stone, 1 metre high, lies near the summit, and a stone mounting block remains on the eastern side.