The Roundhouse is a performing arts and concert venue at the Grade II* listed former railway engine shed in Chalk Farm, London, England. The building was erected in 1846–1847 by the London & North Western Railway as a roundhouse, a circular building containing a railway turntable, but was used for that purpose for only about a decade. After being used as a warehouse for a number of years, the building fell into disuse just before World War II. It was first made a listed building in 1954.

It reopened after 25 years, in 1964, as a performing arts venue, when the playwright Arnold Wesker established the Centre 42 Theatre Company and adapted the building as a theatre. The large circular structure has hosted various promotions, such as the launch of the underground paper International Times in 1966, one of only two UK appearances by The Doors with Jim Morrison in 1968, and the Greasy Truckers Party in 1972.

The Greater London Council ceded control of the building to Camden Council in 1983. By that time, Centre 42 had run out of funds and the building remained unused until a local businessman purchased the building in 1996 and performing arts shows returned. It was closed again in 2004 for a multi-million pound redevelopment. On 1 June 2006, the Argentine show Fuerzabruta opened at the new Roundhouse.

Since 2006, the Roundhouse has hosted the BBC Electric Proms and numerous iTunes Festivals, as well as award ceremonies such as the BT Digital Music Awards and the Vodafone Live Music Awards. In line with the continuing legacy of avant-garde productions, NoFit State Circus performed the show Tabú during which the audience were encouraged to move around the performance space.

The Roundhouse was built as a turntable engine shed (or roundhouse) for the London & Birmingham Railway. Known as the Great Circular Engine House, or the Luggage Engine House, it was built by Branson & Gwyther, using designs by architects Robert B. Dockray and Robert Stephenson. Construction started in 1846 and the building opened in 1847.

Within ten years locomotives became too long for the building to accommodate, and the Roundhouse was used for various other purposes. The longest period of use (50 years, beginning in 1871) was as a bonded warehouse for gin distillers W & A Gilbey Ltd.

In 1964 the premises were transferred to Centre 42, which prepared a scheme to convert the building into "a permanent cultural centre with a theatre, cinema, art gallery and workshops, committee rooms for local organisations, library, youth club and restaurant dance-hall". This was estimated to cost between £300,000 and £600,000 (£7.1 million–£14.2 million in 2024 worth), and was supported by "well-known actors, playwrights, authors, musicians and others". In 1966 the Roundhouse became an arts venue, after the freehold was taken up by the then new Greater London Council. The opening concert was the 15 October 1966 All Night Rave, in which Soft Machine and Pink Floyd appeared at the launch of the underground newspaper International Times. The first major concert took place on New Year's Eve 1966, when a night called Psychadelicamania was headlined by The Who. During the next decade the building became a significant venue for UK Underground music events Middle Earth and Implosion. Many of these were hosted and promoted by Jeff Dexter. Other bands playing at the Roundhouse during this period included Gass, The Rolling Stones, Jeff Beck, The Yardbirds, Zoot Money's Dantalian's Chariot, David Bowie, Jimi Hendrix, Pink Floyd, Led Zeppelin, The Incredible String Band, Fleetwood Mac, Third World War, The Doors with Jefferson Airplane, the Ramones, The Clash with The Jam, Elvis Costello, Elkie Brooks, Otis Redding, and Motörhead, who appeared at the Roundhouse on 20 July 1975. In 1978, Television Personalities referenced the venue on their EP 'Part Time Punks' with the song 'Posing at the Roundhouse'.

While lying in a state of general abandonment in the 1980s, the Roundhouse was used as the main location for the science fiction horror film Hardware by Richard Stanley. Sets were built inside the structure, although the lack of proper soundproofing meant all of the dialogues had to be re-recorded.