If you want a peaceful day out of the busy city, Highgate doesn't really feel like London. The cemetery is interesting and peaceful, there's a tour of the old half which is definitely worth the money. Karl Marx, among others are buried there.
At first a memory of an old relationship, it quickly became my favourite market. Major highlight for the gin tasting with rosemary on a sunny Sunday afternoon.
A non-profit organisation, Raven Row focuses on developing an engaging and intelligent contemporary art programme outside of the highly commercial London art scene. The gallery exhibits established international artists alongside those whose work is often overlooked by the mainstream venues.