City of London

The City of London aka the "Square Mile" is considered the financial core of the metropolis and is almost fully dedicated to commerce. Being an interesting (sometimes overwhelming) mix of Georgian and Victorian architecture, as well as modernist, the City zone is a very nice place for long walks. It is not the most quiet place in London, but its many Churches, dating as far back as the XVII century, can offer you quite an oasis of peace and quiet.