Originally a fortified outpost of the Gaelic McDonagh clan guarding a ford across the River Unsin, it was granted to Cromwellian officer Cornet Edward Cooper in 1663. Astronomer Edward Joshua Cooper transformed it into a Gothic Revival mansion in the 19th century and built the Markree Observatory, which briefly housed the world's largest refracting telescope and where the asteroid 9 Metis was discovered in 1848.
Markree Castle's story is one of radical transformation—from a fortified stronghold of the Gaelic McDonagh clan into an Enlightenment-era private observatory, and finally into a luxury hotel. The earliest incarnation of Markree was a 14th-century fortified outpost, a centre of power for the Irish McDonaghs as they commanded the ford across the River Unsin in south Sligo. Like so many Irish fortresses, its fate was sealed by Cromwell. In 1663, in the aftermath of the Civil War and the Commonwealth period, the lands were granted to Cornet Edward Cooper, a Cromwellian officer, as a reward for his military service. Cooper married Marie Rua, the widow of Conor O'Brien, and their descendants held the estate for nearly four centuries—a remarkable continuity of ownership that allowed for long-term building and refinement in a way that properties under frequent siege or transfer could never achieve.
But Markree's transformation into one of Ireland's most architecturally sophisticated sites came during the early 19th century. In 1802, the castle underwent substantial modernisation, with architect Francis Johnston adding exterior refinements and bringing the structure into fashionable Regency aesthetics. Then, most remarkably, in 1830, Edward Joshua Cooper—a man of the Enlightenment and an accomplished astronomer—established Markree Observatory on the estate. Cooper constructed what was described as 'the most richly furnished private observatory known,' and for several years his refracting telescope ranked as the largest in the world. The quality of his instruments and the clarity of the Irish night sky allowed for significant achievements: in 1848, the observatory discovered the asteroid 9 Metis. Markree became a centre of Irish scientific achievement during an era when such private observatories represented the cutting edge of astronomical research. The observatory remained active until 1902, spanning over seventy years of continuous operation. The winter of 1881 saw another claim to fame: on 16 January of that year, Markree recorded Ireland's lowest officially recognised temperature, −19.1 °C—a record that would stand unchallenged for over a century.
The 19th-century witnessed further architectural development. By 1896, interior improvements brought the castle into the aesthetic of the late Victorian era, and the estate—comprising 300 acres—became known for its sophisticated gardens and carefully managed landscapes. The Corscadden family purchased Markree in 2015 and undertook extensive renovations, converting it into a luxury hotel and restaurant operation while carefully preserving its architectural heritage. Today, visitors can stay within these historic walls, dine where Edward Joshua Cooper once contemplated the stars, and walk the grounds of an estate that witnessed the full sweep of Irish history—from Gaelic clan stronghold through Cromwellian settlement to Enlightenment scientific achievement and modern hospitality.
What to see and do
- Tour the Gothic Revival architecture transformed by Francis Johnston in 1802 and enhanced in 1896
- Learn about Edward Joshua Cooper's Markree Observatory and its role in 19th-century Irish science
- Dine at the hotel restaurant within the historic castle walls, experiencing the interior renovation that preserves period character
- Walk the 300-acre estate and its formal gardens designed and developed across three centuries
- Discover the connection to poet Cecil Frances Alexander (composer of 'All Things Bright and Beautiful'), who may have visited and been inspired by the castle
Visiting Markree Castle
Markree Castle now operates as a 30-room hotel with a public restaurant, making it one of Ireland's few castles where visitors can both tour and dine within the historic structure. Guided tours and restaurant reservations are available through the hotel. The castle is located in south Sligo on a 300-acre estate featuring wildlife habitat and formal gardens. As an active hotel, specific visiting hours should be confirmed in advance. The transformation into a hotel means the interior is actively maintained and preserved, offering visitors a uniquely intimate experience of a working historic site.
Where to stay nearby
The closest castle hotel is Markree Castle, 0.39 km away in Collooney — 14th-century fortified outpost of the McDonagh clan, granted to the Cooper family in 1663 and expanded over succeeding centuries; the estate later hosted a major astronomical observatory.
