The Adelphi Theatre was founded in 1806 as the Sans Pareil ("Without Compare"). In 1819 it took on its present name, which came from the name of a 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"). The present building is the fourth on the site.
The Adelphi Theatre is located in a Grade II listed Art Deco building on The Strand in London's West End.
There has been a theatre on the site since 1806. In 1930 the Adelphi theatre was refurbished and updated to accommodate larger audiences and address safety issues. The structural walls and the entrance at the back of the theatre are all that survive from the old building.