Spires, turrets, clinging ivy and creaking trees give this hulking structure a spooky feel (and, yes, it's reputedly haunted). Charleville Castle was the family seat of the Burys, who commissioned the design in 1798 from Francis Johnston, one of Ireland's most famous architects. Admission is by 45-minute tour only. The castle is 3km southwest of Tullamore; look for the grove of huge ancient oaks.
The interior is spectacular, with ornately plastered ceilings, one of the most striking Gothic-revival galleries in Ireland and a kitchen block built to resemble a country church.