Waterlow Park
A secret jewel of a park. Beautifully landscaped grounds, hills, mature trees, lakes, a walled garden, visitor's centre, café, tennis courts, and children's playgrounds. Bequeathed to the public as a "garden for the gardenless" by Sir Sidney Waterlow in 1889. A visit here combine

A secret jewel of a park. Beautifully landscaped grounds, hills, mature trees, lakes, a walled garden, visitor's centre, café, tennis courts, and children's playgrounds. Bequeathed to the public as a "garden for the gardenless" by Sir Sidney Waterlow in 1889. A visit here combine
Check the official site before travelling; hours and prices can change.
More parks

Hampstead Heath
320 hectares of wild north London — swim the ponds in summer, climb Parliament Hill for the skyline.

Greenwich Park
Royal park with the Observatory at the top — best skyline view east of central.

Regent's Park
Queen Mary's rose garden in June. Primrose Hill at sunset, year-round.
Source: wikivoyage