The Adelphi Theatre in London was founded in 1806 as the Sans Pareil ("Without Compare"), changing its name in 1819 to Adelphi, after the block of 24 unified neoclassical terrace houses occupying the land between The Strand and the River Thames, which had been built by the Adam brothers (Greek: adelphoi, "brothers") as a real estate speculation, in 1768 - 1772, largely demolished in 1936 (illustration, left). The present building is the fourth on the site.

The Theatre is well known as the place where Andrew Lloyd Webber's Cats Musical Video was recorded in 1998.

Since 1997 the venue has been the setting for the popular West End musical, Chicago.