The Royal Festival Hall is a 2,700-seat concert, dance and talks venue within Southbank Centre in London, England.

[5] A large head and shoulders bust of Nelson Mandela (by Ian Walters, created in 1985) stands on the walkway between the hall and Hungerford Bridge approach viaduct.

The acoustical consultant was Hope Bagenal, working with members of the Building Research Station; Henry Humphreys, Peter Parkin and William Allen.

But the strength of the design was the arrangement of interior space: the central staircase has a ceremonial feel and moves elegantly through the different levels of light and air.

"[11] The hall they built used modernism's favourite material, reinforced concrete, alongside more luxurious elements including beautiful woods and Derbyshire fossilised limestone.

The ceiling was wilfully sculptural, a conceit at the very edge of building technology and, as it turns out, way beyond the contemporary understanding of acoustics.

It was designed as a well-balanced classical instrument embracing a number of rich and varied ensembles which alone or in combination could equal the dynamic scale of any orchestra or choral grouping, in addition to coping with the entire solo repertoire.

This was partially attributable to the fact that some of the original specifications for room surfaces determined by the acoustic consultants were ignored in the building process.

Leo Beranek, an American acoustics engineer who had undertaken measurements of all of the world's leading concert halls, had identified that the interior treatment of the auditorium was absorbing too much sound.

This was considered too costly, particularly as any hypothetical gain in 'warmth' or 'resonance' might well be by the sacrifice of other positive qualities for which the Hall was generally esteemed, for example, its clarity, its comparative uniformity of acoustic response and its freedom from echo.

[23] It was known that the ancient Greeks had developed the technique of using vases built into their auditoria which added resonance to strengthen tone or improve its quality, though the effect was very weak.

It was switched off in 1998, which returned the acoustics to their poor state, so bad that they make performers who play in it "lose the will to live", according to Sir Simon Rattle.

[27] The interior of the concert hall space was almost entirely intact until this re-modelling, which saw its stage canopy and walls rebuilt in plainer more rectangular forms.

On the advice of acoustics firm, Kirkegaard Associates, the lack of reverberation and the difficult performance conditions for musicians were corrected by changes in the fabric of the auditorium.

The tapestries on the back walls of the boxes were gathered up to increase reverberation, but can be redeployed, together with additional absorbent blinds above the stage and around the Hall whenever needed.

Theatre consultants Carr & Angier worked with ISG Interior Exterior and Stage Technologies to create a new working space over the stage area with four large movable lighting bridges, capable of load sharing to lift large touring productions without the need for custom rigging.

[29] During the 2000s a building comprising seven commercial units was erected opposite the western side of the hall, with many of the Southbank administrative offices above.

The organ has been reconfigured to suit the new architectural and acoustic requirements: its depth has been reduced by 110 cm, but the basic principles of the layout have been respected.

Further work including re-balancing the pipework followed and was completed in time for the re-inauguration of the organ on 18 March 2014, exactly 60 years since it was first inaugurated.

The organ sounds uncomfortably constrained in the hall acoustic and is seldom played, either for recitals or to accompany orchestral concerts.