My friend Lola challenged me to do a Classical building, as I usually prefer the Gothic and Elizabethan. She actually wanted me to do the Edinburgh Art Gallery, but I did my favourite classical house instead, sorry.
This is Chiswick House in London (Leen, you will recognise this). It was built as a party house for Lord Burlington and modelled after an Italian villa. Inside it is all interconnecting rooms for eating, socialising and dancing. Originally, the larger house(for actually living in) stood alongside but sadly was demolished.
The house also has stunning landscape gardens. It is a great place to visit. The house belongs to English Heritage and there are details here.