Whispering gallery to the walls, an effect that was discovered in the whispering gallery of St Paul's Cathedral in London. The extent to which the sound travels at St Paul's can also be judged by clapping in the gallery, which produces four echoes. Other historical examples are the Gol Gumbaz mausoleum in Bijapur and the Echo Wall of the Temple of Heaven in Beijing. A hemispherical enclosure will also guide whispering gallery waves. The waves carry the words so that others will be able to hear them from the opposite side of the gallery. The gallery may also be in the form
National Portrait Gallery, London National Portrait Gallery, London The National Portrait Gallery (NPG) is an art gallery in London housing a collection of portraits of historically important and famous British people. It was the first portrait gallery in the world when it opened in 1856. The gallery moved in 1896 to its current site at St Martin's Place, off Trafalgar Square, and adjoining the National Gallery. It has been expanded twice since then. The National Portrait Gallery also has regional outposts at Beningbrough Hall in Yorkshire and Montacute House in Somerset. It is unconnected to the Scottish National Portrait Gallery in Edinburgh, with which