A qualified London tour guide told me that 40% of the city is green space, much of it occupied, of course, by the Royal Parks, large tracts of which are regularly used by the general public.
In Kensington Park, there were walkers, joggers and families a-plenty, enjoying the quiet beauty of the area overlooked by the palace where Queen Victoria was born and Lady Diana lived. In fact, a memorial fountain nearby commemorates her too-short life. When told it was about half an hour's walk away in adjacent Hyde Park, I reluctantly decided to save my foot power for later.
The London Tube, or Underground is the world's oldest transit system. The Baker Street Station is older than Canada; it opened in 1863. Some of the tunnels, like those on the District Line, are shallow cut and cover style, while others lie very deep below ground. Hampstead station on the Northern Line is almost one hundred ninety-two feet deep, according to David Long (The Little Book of the London Underground, The History Press, 2009).
As below, so above. Yesterday I walked all over the elevated world of the Barbican Centre and surroundings, climbing up to the platforms somewhere near St. Paul's Station on the Central Line and descending finally, at Moorgate Station, located on along the Hammersmith and City, Circle and Metropolitan Lines.
Also above ground, the overground trains connect to the subterranean ones, mainly serving the areas outside of the central city.
The buses of London are layered, like the city itself, and a ride on the top of a double decker, especially an open top one, is de rigeur for any tourist who wants to see the city. From the front seat of a big red London bus, the visitor can enjoy not only great views of the streets, but many astonishing architectural flourishes that are invisible from street level.