the Whispering Gallery

Từ điển Oxford Advanced Learner 8th

the Whispering Gallery [the Whispering Gallery] BrE NAmE
the famous ↑gallery (= a raised platform along the inner wall of a building) that goes all the way round the inside of the ↑dome of ↑St Paul's Cathedral in London. It is well known for the way it carries sounds: if a person ↑whispers close to the wall on one side of the gallery, they can be heard by another person close to the wall on the other side of the gallery, 107 feet/32 metres away.