Not the most exciting place inside, but a lovely rooftop area which not all that many people seem to know about, 2 mins walk from Old St station. If it’s packed then The Red Lion is just up the road.
I'm a big fan of Richard Serra. As this is the train station I use to pass in and out of London. I think it's safe to say i've spent more time gazing and contemplating this art work than any other on earth! The steel monolith sits in a rather petite amphitheatre with surrounding step/seats. During the week, it's packed with picnicking stray commuters. I just love sitting there.
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.