LDN is a mobile phone abbreviation for London. It can also refer to:
- LDN Wrestling, a London-based professional wrestling promotion.
- London Daily News, the short-lived London newspaper owned by British newspaper tycoon Robert Maxwell
- BBC London, formerly known as BBC LDN
- "LDN" (song), a 2006 single by Lily Allen
"LDN" (shorthand for, and pronounced as, "London") is a song by English recording artist Lily Allen. It was co-written by Future Cut, and features a Colombian porro from the country's Caribbean coast. The song was originally released on strictly limited edition 7" vinyl (500 copies) in the UK on 24 April 2006, accompanied by album track "Knock 'Em Out", and was re-released in September following the huge success of Allen's first mainstream single "Smile".
The re-release peaked at number six on the UK Singles Chart. The song is used in the soundtrack of the film The Nanny Diaries, and in the trailer for Happy-Go-Lucky. This song was number 30 on Rolling Stones list of the 100 Best Songs of 2007. In 2008 the song was included in the soundtrack of the Mike Leigh film Happy-Go-Lucky. Allen claims that the inspiration for the song was William Wordsworth's poem " Composed upon Westminster Bridge, September 3, 1802".