David Filip: Largest public park in the city, also the oldest, established by Joseph II. Check out the dedication plaque Josephus II [Secundus] Publico MDCCLXXXVII [1786].
David Filip: This is the only Irish Munro you can bag as a daytrip when you're based in Dublin. All of the access parking spots are within 90min drive from central Dublin if you set out early, by 6am in summer.