Markree Castle

Collooney, County Sligo, Ireland, Ireland

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Markree Castle is a historic castle near Collooney in County Sligo, Ireland, with origins dating back to the 17th century when the Cooper family acquired the estate.

The present castle largely reflects major expansions and redesigns carried out in the early 19th century, creating the impressive Gothic-style residence seen today. The castle is particularly famous for its scientific heritage. In the 1830s, the Cooper family established the Markree Observatory on the estate, which housed the largest refracting telescope in the world at the time.

The observatory gained international recognition, and the asteroid 9 Metis was discovered there in 1848, making it an important site in the history of astronomy. Today, Markree Castle is a beautifully restored historic hotel surrounded by parkland and the River Unshin. Renowned for its architecture, rich history, and connections to science and Irish heritage, it remains one of County Sligo’s most notable landmarks.