The Paul Hamlyn Hall is a large iron and glass structure adjacent to, and with direct access to, the main opera house building [Royal Opera House or Covent Garden]. The hall now acts as the atrium and main public area of the opera house, with a champagne bar, restaurant and other hospitality services, and also providing access to the main auditorium at all levels.

The building was formerly known as Floral Hall. It was originally built by the Opera House to house a flower market (also selling fruits and vegetables), hence the name. It was designed by Edward Middleton Barry and opened in 1860. After being used as a concert hall, it became part of the Covent Garden Market in 1887. A fire broke out in the building in 1956, after which it sat derelict. It was acquired by the Opera House in 1977 and used as storage space.[38]

Wikipedia