Desmond Castle in Askeaton in Co Limerick, regarded as one of the most significant medieval castles in Munster, is finally opened to the public after over a decade of painstaking conservation and restoration work, costing over €1.6 million.

Originally a Norman castle, it dates back to 1199, but was principally associated with the Earls of Desmond, the prominent family who ruled Munster for several hundred years from the 1400s.

It was a natural fortress built on a rocky outcrop in the middle of the River Deel, which gave it natural height and a good defensive position against its enemies, and strategically located close to the Shannon estuary if need of escape.

It is also unusual historically in that it is a complex of buildings including Desmond Castle, the Halla Mór or banqueting hall, and a Hell Fire Club, added to the grounds in the 1700s.

However the site has been dangerous for decades, and the Office of Public Works has been involved in a major restoration project there for the past 13 years restoring and conserving the centuries-old stone buildings and making it safe for public access.

 OPW Guide Diane Nolan, who has been supervising the restoration project, describes it as one of the most significant historic castles from the late medieval period anywhere in Munster.

"It was predominantly associated with the Desmond family who were the ruling family and as such this was their HQ," she said.

"They were also the local Justices so courts were held in the banqueting hall, as well as town hall meetings.

"It was so significant that the Desmonds signed a treaty here with the King of France in 1523 against their common foe, the English Crown, only for that treaty to be dismantled two years later when the English and French dropped their hostilities, leaving the Desmond family exposed," she said.

The castle was also almost destroyed by Cromwellian forces in 1652, and the large hole from Cromwell's canons is still evident in the castle wall.

A Hell Fire Club was also built on the site in the 1700s.

These were regarded as houses of ill repute which started in London, and were frequented by men allegedly involved in nefarious activities like drinking scalteen, a drink of whiskey and butter, and devil worship, and other activities frowned upon by society at the time.

The castle was also used as a barracks in the early 1900s and was used as a base by anti-treaty forces during the Civil War.

James O'Donoghue, who is the OPW senior stonemason foreman on the site, said the restoration and conservation is very demanding and specialist work, which cannot be rushed.

He said it is an amazing opportunity and privilege to be working among such historic buildings and discovering along the way how stonemasons of centuries past did their work.

He said the site also allowed them to introduce an apprentice scheme for young stonemasons to show them how such historic buildings can be restored and conserved.

Desmond Castle is also one of the first OPW historic heritage sites to be open while the restoration work is ongoing, allowing the public to view the stonemasons at their work.

The opening of the castle with its centuries of history and stories, will also provide a welcome tourism boost for the town of Askeaton.

Anthony Sheehy, who has been operating as a local history guide for many years in the town, said the safe opening of the site is one of the best things to happen to Askeaton in decades.

"For years this was an unsafe site, but it is steeped in so much history. I believe it will open the town up to so many more tourists in the future, anxious to visit one of the best medieval castle sites anywhere in the country," he said.

The castle is now open until the end of October for four guided tours per day, which must be booked.