This happens to be “The Red Bus”. For E$17 I purchase not only a tour ticket but also a single fare ticket for a ride to the airport.
The bus tour covers a lot of interesting sites from Kilmainham Jail where the famous Irish nationalist Robert Emmet was hanged and beheaded in 1803 to Phoenix Park where the Irish President resides.
For me, the most important stop on the tour is Stop 14 where a man at one time lived with his wife and twenty one children in the mid eighteen century. Once the entrance to the old walled city, St James Gate since 1759 has been the home of the Guinness Brewery and will be so for less say the next 8,747 years.