One of Ireland’s famous historic landmarks may be at risk.

Beamish and Crawford, the oldest stout brewery in Ireland, will close its doors by the end of May, and Heineken, its new owner, plans to sell the site to the highest bidder.

Originally, the brewery was to shut down in March, but logistical problems delayed its closure.

Heineken purchased the company in 2008, and the products currently brewed at the ancient Cork plant will move to the nearby Heineken Brewery.

Beamish and Crawford was founded in Cork in 1792 by William Beamish and William Crawford, who helped make the brewery one of the largest in Ireland. The brewery itself was in use for brewing as early as the 1600s, making it the most ancient brewery in Ireland.

Heineken confirmed that they will sell the four-acre site, but not until the brewery is completely decommissioned, which could take up to 18 months. Their Corporate Affairs Manager, Declan Farmer, said that though the company is aware of the site’s historical significance, once they sell it, they will no longer be involved.

Historians and heritage campaigners are worried about the fate of the Irish landmark and the famous Tudor counting house on the premises.

The National Conservation and Heritage Group of Ireland, which fought for Guinness’ development of the Guinness Storehouse in Dublin, wants Heineken to create a similar micro-brewery style attraction at the site of the historic Beamish brewery. The group says it will campaign on the streets to save the site if Heineken does not “engage with them in a meaningful way.”

Beamish and Crawford make Beamish stout, its flagship brand, and Beamish Red, a sweet ale, but Heineken will not sell the products anywhere outside of Ireland.

Beamish and Crawford employed 160 people, 80 of which have already been laid off. Another 40 members of the workforce have been transferred to the Heineken Cork headquarters, while the remaining 40 will oversee fermentation and bottling of the beer at the Heineken plant.