London has numerous venues for rock and pop concerts, including the world's busiest arena the o2 arena and other large arenas such as Earls Court, Wembley Arena, as well as many mid-sized venues, such as Brixton Academy, the Hammersmith Apollo and the Shepherd's Bush Empire. Several music festivals, including the Wireless Festival, South West Four, Lovebox, and Hyde Park's British Summer Time are all held in London. The city is home to the first and original Hard Rock Cafe and the Abbey Road Studios where The Beatles recorded many of their hits. In the 1960s, 1970s and 1980s, musicians and groups like Elton John, Pink Floyd, David Bowie, Queen, The Kinks, The Rolling Stones, The Who, Eric Clapton, Led Zeppelin, The Small Faces, Iron Maiden, Fleetwood Mac, Elvis Costello, Cat Stevens, The Police, The Cure, Madness, The Jam, Dusty Springfield, Phil Collins, Rod Stewart and Sade, derived their sound from the streets and rhythms vibrating through London.

What famous chain of music-themed restaurants opened its first establishment in London?