In which of these countries is Carlow Castle located?

Carlow Castle (Irish: "Caisleán Cheatharlach") is located near to the River Barrow in County Carlow, Ireland. It was built between 1207 and 1213, and is a National Monument of Ireland.

The earliest written record of this castle is from 1231 but it does not name its builder. It is widely assumed that the castle was built by William Marshal the elder in the time period between 1207 and 1213 which he spent in Ireland. William Marshal, 2nd Earl of Pembroke (1190 – 6 April 1231) was a medieval English nobleman and was one of the sureties of "Magna Carta".

The castle was handed over to the crown in 1306, granted in 1312 to Thomas Plantagenet, confiscated by the crown in 1537 as the landlords were absent, bought by the Earl of Thomond in 1616, changed hands multiple times until it was taken by Oliver Cromwell in 1650 but was later returned to the Earl of Thomond.

In 1814 the castle was widely destroyed in an attempt to create more space for the conversion into a lunatic asylum with the help of explosives. Just the outer face of the west wall and the two neighbouring towers could be preserved.

The Republic of Ireland is a country in north-western Europe consisting of 26 of the 32 counties of the island of Ireland, with a population of about 5.4 million.The capital and largest city is Dublin, on the eastern side of the island, with a population of about 1.5 million. The sovereign state shares its only land border with Northern Ireland, part of the United Kingdom.