No, not a gambling haunt. It gets its name from the meaning of Casino as a "small house". Despite its name and "apparently" small size, this house is full of optical trickery. It has 16 finely decorated rooms and is one of the finest 18th century neo-classical buildings in Europe.
It was designed by Sir William Chambers as a pleasure house for James Caulfield, 1st Earl of Charlemount. It has a remarkable history and architectural structure.
It is open to the public for visits. Last admission: 45 minutes before closing.
Follow the link for more info to get the specific opening hours, admission fees and details of bus routes. Also accessible by DART (Clontarf stop with a 25 minute walk to the Casino).