The R666 road is a regional road

Regional road

A regional road in Ireland is a class of road not forming a major route , but nevertheless forming a link in the national route network. There are over 11,600 kilometres of regional roads. Regional roads are numbered with three digit route numbers, prefixed by "R" A regional road in Ireland is a...

 in Ireland

Republic of Ireland

Ireland , described as the Republic of Ireland , is a sovereign state in Europe occupying approximately five-sixths of the island of the same name. Its capital is Dublin. Ireland, which had a population of 4.58 million in 2011, is a constitutional republic governed as a parliamentary democracy,...

 which runs west-east from the R639

R639 road

The R639 road is one of Ireland's regional roads. Once designated the N8 national primary road , it was reclassified in stages as the R639 following the progressive opening of sections of the M8 motorway, which rendered the single carriageway N8 redundant as a national primary road...

 in Fermoy

Fermoy

Fermoy is a town in County Cork, Ireland. It is situated on the River Blackwater in the south of Ireland. Its population is some 5,800 inhabitants, environs included ....

 town centre to the bridge over the River Blackwater

Munster Blackwater

The Blackwater or Munster Blackwater is a river which flows through counties Kerry, Cork, and Waterford in Ireland. It rises in the Mullaghareirk Mountains in County Kerry and then flows in an easterly direction through County Cork, through Mallow and Fermoy...

 on the outskirts of Lismore

Lismore, County Waterford

Lismore is a town in County Waterford, Ireland. It is located where the N72 road crosses the River Blackwater.-History:It was founded by Saint Mochuda, also known as Saint Carthage. In the 7th century, Lismore was the site of the well-known Lismore Abbey. It is also home to Lismore Castle, the...

. The road passes through Ballyduff

Ballyduff, County Waterford

Ballyduff is a village in County Waterford, Ireland. It is also a parish in the Roman Catholic Diocese of Waterford and Lismore.-Location and access:...

, and beneath the River Blackwater

Munster Blackwater

The Blackwater or Munster Blackwater is a river which flows through counties Kerry, Cork, and Waterford in Ireland. It rises in the Mullaghareirk Mountains in County Kerry and then flows in an easterly direction through County Cork, through Mallow and Fermoy...

 viaduct which carries the M8 motorway

M8 motorway (Ireland)

The M8 motorway is an inter-urban motorway in Ireland, which forms part of the road from the capital - Dublin - to Cork city. The 149 km motorway commences in the townland of Aghaboe, County Laois and runs through the counties of Kilkenny, North Tipperary, South Tipperary and Limerick,...

. The R666 begins in Fermoy as the Rathhealy Road. From here to its merger with the R667 road

R667 road

The R667 road is a regional road in Ireland. The route runs from its junction with the N8 1 km from Kilworth for approximately 5 km until it meets the R666 road northeast of Fermoy. The R667 was once part of the main road from Dublin to Cork, and was mapped as such by Herman Moll in his New Map of...

 3km south of Kilworth

Kilworth

Kilworth is a village in north County Cork. It is also one half of the parish of "Kilworth and Araglin" in the Roman Catholic Diocese of Cloyne.-Loation and access:...

, the R666 was once part of the historic road linking Dublin and Cork

Cork (city)

Cork is the second largest city in the Republic of Ireland and the island of Ireland's third most populous city. It is the principal city and administrative centre of County Cork and the largest city in the province of Munster. Cork has a population of 119,418, while the addition of the suburban...

. It was mapped as such by Herman Moll

Herman Moll

Herman Moll , was a cartographer, engraver, and publisher. Moll moved to England in 1678 and opened a book and map store in London...

 in his 1714 New Map of Ireland.

The route is 28 km (17.4 mi) long.

Locally, the road is sometimes humorously known as the road to hell from its name being the same as the Number of the Beast

Number of the Beast

The Number of the Beast is a term in the Book of Revelation, of the New Testament, that is associated with the first Beast of Revelation chapter 13, the Beast of the sea. In most manuscripts of the New Testament and in English translations of the Bible, the number of the Beast is...

.

See also

• Roads in Ireland
  Roads in Ireland
  The island of Ireland, comprising Northern Ireland and the Republic of Ireland, has an extensive network of tens of thousands of kilometres of public roads, usually surfaced. These roads have been developed and modernised over centuries, from trackways suitable only for walkers and horses, to...
  
  
• Motorways in Ireland
• National primary road
  National primary road
  A national primary road is a road classification in the Republic of Ireland. National primary roads form the major routes between the major urban centres. There are over 2,700km of national primary roads. This category of road has the prefix "N" followed by one or two digits...
  
  
• National secondary road
  National secondary road
  A national secondary road is a category of road in Ireland. These roads form an important part of the national route network, but are secondary to the main arterial routes which are classified as national primary roads. National secondary roads are designated with route numbers higher than those...
  
  
• History of roads in Ireland
  History of Roads in Ireland
  There have been routes and trackways in Ireland connecting settlements and facilitating trade since ancient times and the country now has an extensive network of public roads connecting all parts of the island.-Early history:...