Camley Street Natural Park
A 2-acre nature reserve amid the industrial wasteland just north of King's Cross Station. This lovely little park gives visitors interested in nature the opportunity to learn about the work of the London Wildlife Trust who administer this and 26 other reserves in London. This is

A 2-acre nature reserve amid the industrial wasteland just north of King's Cross Station. This lovely little park gives visitors interested in nature the opportunity to learn about the work of the London Wildlife Trust who administer this and 26 other reserves in London. This is
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