This is a tower house, otherwise known as a castle but was actually more of a fortified dwelling.
This one dates from the 1500s and is said to have been one of three in this locality, the other two now long destroyed.
Now in ruins it was built from granite and stood close to the upper reaches of the River Liffey that flows from the Wicklow Mountains in a circular route to the Irish Sea through Dublin City.
And what a day it was, take a few moments to walk around this impressive structure with me in this short video.
Remember, you get one castle at Threecastles.
