I was wondering what are the castles that are closest to Dublin that I can visit. I know there is Dublin Castle, but I wanted to try to visit some of the ones that are maybe outside of the city. i’m only there for three days, so I don’t want to go someplace too far away from the city center thank you.

I visited Powerscourt from Dublin years ago by bus & stayed overnight nearby but you could certainly return after a visit. The house started life as a castle and over the years has become more a stately home. The gardens are the big attraction with only, I believe, a restaurant & shop inside the building.

Here’s their website: https://powerscourt.com/

Rome2rio.com will show you how to get there on public transport if you won’t have a car.

Malahide Castle is easily enough reached by DART.

Malahide does seem like the most convenient "intact" castle.

Also, iIf you're interested at all in historic ruined castles, Maynooth Castle's keep and portions of its outer walls remain and it's a direct trip by train or bus.

Thanks for the replies!