Roscrea owes its beginnings to a 5th-century monk, St Cronan, who set up a way station for the travelling poor. Most of the historical structures are on or near the main street, Castle St.
Roscrea Castle, a 13th-century stone edifice right in the town centre, was started in 1213 and is remarkably intact. There are two fortified stone towers, surrounded by walls. Look closely and you can see where the original drawbridge was installed. Inside the courtyard stands the early 18th-century Damer House, the Queen Anne-style residence of the Damer family.
Inside you'll find the Roscrea Heritage Centre, which contains some interesting exhibits, including one on the medieval monasteries of the Midlands and another on early 20th-century farming life. There's a peaceful walled garden by the house.
Up to eight Bus Éireann buses stop at Roscrea between Dublin (€11, two hours) and Limerick (€9.50, 1½ hours).