Established in 1831, the 28-hectare Dublin Zoo just north of the Hollow is one of the oldest in the world. It is well known for its lion-breeding program, which dates back to 1857, and includes among its offspring the lion that roars at the start of MGM films. You'll see these tough cats, from a distance, on the 'African Savannah', just one of several habitats created in the last decade or so.
The zoo is home to roughly 400 animals from 100 different species, and you can visit all of them across the eight different habitats, which range from an Asian jungle to a family farm, where kids get to meet the inhabitants up close and milk a (model) cow. Sadly, a strain of avian flu in 2017 meant that all of the zoo's birds were moved indoors so as to avoid interaction with native, wild species.
There are restaurants, cafes and even a train to get you round.