Wavertree Playground, also known locally as The Mystery, was one of the first purpose-built public playgrounds in the United Kingdom. It is based in the Wavertree area of Liverpool, England.
In May 1895, a stately home called The Grange was demolished and it looked inevitable that the estate it was based within would be used as building for the increasing suburbs of Liverpool. Much to the surprise of Liverpool society, it was however announced that an anonymous donor had purchased the Grange estate together with some adjoining properties, and was presenting the whole 108 acres (0.44 km2) to the City of Liverpool.
The donor had levelled and grassed the area – eradicating the ornamental lake that was once a feature of the grounds – and suggested the name 'Wavertree Playground'. It was to be a venue for organised sports, and a place for children from the city's public schools to run about in, not a park for 'promenading' in the Victorian tradition. He expressed the hope that the City Council "might approve of giving it a fair trial for this purpose ... before appropriating it for any other use".
The mysterious donor's offer was accepted by the council; the playground was opened by the Lord Mayor of Liverpool amid great celebrations on 7 September 1895. There was a march past of 12,000 children, after which, the Daily Post reported, "the children were liberally regaled with cakes and milk". Juvenile sports, a gymnastics exhibition and Morris dancing followed, and finally "for upwards of two hours, the sky was brilliant" with a fireworks display watched by an estimated 60,000 people.