Mentioned by Lonely Planet Top Choices
Top things to do in Wales
"Devoted mainly to natural history and art, this grand neoclassical building is the centrepiece of the seven institutions dotted around the country that together form the Welsh National Museum. It's one of Britain's best museums; you'll need at least three hours to do it justice, but it could easily consume the best part of a rainy day. On-site parking, behind the museum, is £6.50."