The performance art is part of internationally recognized Portuguese artist Jo�o Onofre's touring sculpture titled Box Sized Die. "In each location the sculpture travels to, Onofre invites a local death metal band to play, on this occasion Unfathomable Ruination," says the City of London's official website.

"The box is soundproofed, determining and restricting the performance's duration to the length of time in which the oxygen is expended. Outside the cube, viewers observe its strange vibrations, only viewing the band's entrance and exit to the performance space."

Onofre's iron box is part of London's free art exhibition, Sculpture in the City, a collaboration between the City of London Corporation, local businesses and the art world to create open-air art exhibitions around the city, explained Culture24.org.