Lancaster Gate, near the Long Water). It was one of the first pictures I took in London.
But it didn't take a day to discover that London doesn't have nearly enough trash cans, or rest rooms ('Toilets'). I spent way too much time looking for one or the other. Also, I don't think I saw one water fountain all week.
Brits can do trains, and they have lovely accents, and the history is pervasive, when it comes to public cleanliness and hygiene, we win.