Syon is one of the last great houses of London, and has been in the family of the present owners for more than 400 years. Profoundly historic, the House holds a wealth of art within its grand classical interiors, while the Park and Gardens feel like deep countryside, although barely nine miles from Charing Cross.

https://www.syonpark.co.uk/

Speakers' Corner is a traditional site for public speeches and debates since the mid 1800's when protests and demonstrations took place in Hyde Park.

https://www.royalparks.org.uk/parks/hyde-park/things-to-see-and-do/speakers-corner

The Phoenix Garden is a community garden and registered charity, managed by volunteers, created to provide a green retreat from the stresses of London's West End and a vital habitat for urban wildlife.

The Crystal Palace Park is English Heritage Grade II listed and located within the London Borough of Bromley and on the boundary of the London Boroughs of Croydon, Lambeth, Lewisham and Southwark.

The Isabella Plantation is a 40 acre woodland garden set within a Victorian woodland plantation planted in the 1830's. First opened to the public in 1953, it is best known for its evergreen azaleas, which line the ponds and streams and at their peak of flower in late April and early May.

Holland Park is spread across 54 acres of what used to be the grounds of Cope Castle, a large Jacobean mansion hidden in the woods. It was built by Sir Walter Cope in the early 17th century, who became Chancellor of the Exchequer under King James 1. It was renamed Holland House after the Earl of Holland’s wife Lady Rich inherited the property. 

Every year millions of Londoners and tourists visit The Green Park, the smallest of the capital's eight Royal Parks.

Victoria Tower Gardens, officially opened in 1914, lies at the heart of Westminster, bordered by the Houses of Parliament, the River Thames, Millbank and Lambeth Bridge.

Every year millions of Londoners and tourists visit Bushy Park, the second largest of the capital's eight Royal Parks.

The Garden Museum was set up in 1977 in order to rescue from demolition the abandoned ancient church of St Mary’s.

Osterley Park is one of the best preserved country estates in London. It was created by architect Robert Adam and is now managed by the National Trust.

https://www.nationaltrust.org.uk/osterley-park-and-house