Three of Ireland’s most prominent astronomical sites will be put forward for world heritage site status from the United Nations Educational, Scientific and Cultural Organisation, known as Unesco. Birr Observatory in Co Offaly, Dunsink Observatory in Dublin and the Armagh Observatory and Planetarium are part of a cross-Border plan to highlight the country’s legacy in astronomy. The three sites formed the Astronomical Observatories of Ireland (AOI) in 2023 to create a programme of joint work. They have been added to the world heritage tentative list for Ireland and the UK. This is the first step in the process of getting world heritage status for a site. Ireland already has three Unesco world heritage sites: Brú na Bóinne in Co Meath, Skellig Michael, Co Kerry, and the Giant’s Causeway and Causeway coast in Co Antrim. The three observatories were added for consideration to the Irish list, which also includes the Neolithic passage tomb landscape of Co Sligo, the transatlantic cable ensemble (Kerry and Canada) and the royal sites across the island. Birr Castle Demesne chairman and director of the Dunsink Observatory Prof Peter Gallagher said Ireland’s contribution to astronomy in the 19th century “cannot be overstated”. The Birr Telescope, built by William Parsons in 1845, was the largest telescope in the world for 70 years. Parsons was the first to observe spiral galaxies. William Rowen Hamilton, who used Dunsink Observatory regularly, was a world-leader in optics and quantum mechanics which are still used in astronomical study. Professor Gallagher said preparation for the tentative list took five years and it may take another five years before Unesco status was granted, but the wait would be worth it. “We need to protect the heritage of all three sites, conserve, preserve as well as educate on the importance of science for society and to inspire the next generation,” he said. The Dunsink Observatory is run by the Dublin Institute for Advanced Studies (DIAS). Its chief executive, Dr Eucharia Meehan, said gaining tentative status was a “fantastic recognition of the observatories’ unique, historical heritage and very apt on this World Heritage Day”. Dr Meehan said: “We also acknowledge the support of our three local authorities – Fingal County Council, Offaly County Council, and Armagh City Banbridge and Craigavon Borough Council, each of whom has embraced the significance and value of the observatory in their area.” Armagh Observatory was founded in 1790 and is the longest continuously operating observatory in the UK or Ireland. Its director, Professor Michael Burton, said Armagh had pioneered the modern astronomical observatory with a telescope mounted on a pier inside a rotating done in the 18th century. “We look forward to now working with our partners in Birr and Dunsink in seeking designation to the UK’s tentative list, the next stage in the journey towards seeking Unesco accreditation,” he said. The National Monuments Service and OPW will now focus on supporting the Historic Astronomical Observatories of Ireland to develop their nomination in partnership with Northern Ireland. Minister for Heritage James Browne said the addition of the Astronomical Observatories of Ireland to the tentative list was the “first formal step on an exciting journey towards World Heritage inscription for three remarkable observatories”. He said: “These places of trailblazing scientific endeavour epitomise historical collaboration across the island. They showcase our remarkable heritage on the global stage, and the journey of this project in the years will strengthen North-South co-operation greatly with shared benefits for these places and their communities.”