What is the most beautiful noun phrase in English? Cellar door is the favourite of many famous writers, including Dorothy Parker, J. R. R. Tolkien, and C. S. Lewis. But no-one is quite sure who said it first.
Possibly the source is an 1894 song lyric “slide down my cellar door,” which sounds pretty dodgy.
The term for the study of the aesthetics of language is phonoaesthetics, which to me is a prettier word than cellar door, as is the line of Emily Dickinson poetry cited in the Wikipedia article “Oars divide the Ocean, / Too silver for a seam.”