Dublin is a great city with friendly people. We did not meet one rude person the whole trip. Most places in Dublin can be reached by walking from the city center. We just happened to be in town when Ireland played Australia in Rugby. Unique experience for Americans. A popular night spot is the Temple Bar area. It is a tourist spot and worth checking out briefly but we preferred to drink with the locals at their pubs, outside of Temple bar.
Kilmainham Gaol Museum is pictured below. It is a prison from 1790 with a lot of history. Well worth the visit.