London is so vast I end up spending hours travelling on trains. They are by far the best way to travel around on and are always full of weird and wonderful characters.
The walk along the South Bank from Westminster to Tower Bridge will take you past a plethora or interesting sights and cultural hotspots. There's always something interesting going on too.
London has great green spaces. There are large royal parks and small public gardens, hidden allotments and roof terraces. Each one has its own identity and characteristics and everyone has their favourite. In summer they become extensions of people homes, you see girls sunbathing from 9 am and the endless picnics mean you can eat 3 meals a day in the park. My favourites - St James Piccadilly Gardens, Hyde Park, Barbican Conservatory.
There are many great parks in London to choose from, but Hampstead Heath is by far my favourite; a lido, Parliament Hill with a great view of the city, ponds, woods and plenty of space. It’s a great place to hang out in the summer, but also presents a lovely walk in the winter. Address: (As it’s so big obviously it doesn’t really have a specific address but there are 2 main entrances) Entrances by Gospel Oak or Hampstead Heath Entrance.