'Belsize' comes from the French bel assis, beautifully situated.
The name is recorded in the 14th century as Bel-assis. The manor dates back to 1317, when, as part of the Manor of Hampstead, it was left to the monks of Westminster Abbey. 'Park' recalls a 17th-century manor house and its parkland, which once stood here; from 1721 to 1745 the grounds were pleasure gardens, with concerts, dancing and racing.