Must dos for a 3 day trip to Ireland.

Where in Ireland are you flying to? Rick Steves Ireland book has great walking tours.

Dublin - Trinity College (Book of Kells), Goul, Guiness

Cliffs of Moher are incredible but not sure of your mode of transportation while you are there.

Assuming you’re flying into Dublin on the eastern side of Ireland, and not Shannon Airport in the west. The western side of the country is actually more our cup of tea than capitol, big-city Dublin, but with 3 days, stick to the east so you’re not spending a lot of that time traversing the country on a bus or train.

Key sights in Dublin are Trinity College, the Old Post Office, the Kilmanhain Gaol (jail), and at least one pub with traditional (trad) Irish music - try The Cobblestone on the west end of town.

Mystical ancient burial mounds and Stone-Age monuments to the north of Dublin, like Newgrange, are doable on a day tour from Dublin. We booked a private tour with Anthony Murphy, an expert who’s authored books on the subject, and highly recommend him. Book your tour ASAP, and also book a time for a guided tour at the Gaol to ensure you get a spot - a time slot later in the day worked for us, and be sure to visit the museum at the Gaol, too.

We rented an apartment in Dublin, but with only 3 days (4 nights?) you may need a hotel. Be sure to have Irish Oatmeal at least one day, and a full Irish Fry for breakfast at least once, too. Irish seafood is fantastic - gave salmon for supper and you won’t be sorry. Lamb, too.

The RS Ireland book has Dublin sights & things to do ranked by priority stars, so with a short time you'd prioritize those with the most stars -- naturally influenced by the ones that are personally of most interest to you. That's what we did (we arrived on a Friday morning and flew onward Sunday evening) and it worked out great.