My gf and I started a project to spend a day in each borough of London, a couple of years ago. Originally we were aiming to complete it in one or two years, but life got in the way; it's paused at 16 out of 33 right now. I'm a born and bred Londoner in my mid-40s, and in the course of this (despite only being halfway through) have been to so many places I'd never visited - we research interesting cultural, historical, and alcohol-vending places to visit beforehand and it's ludicrous amounts of fun.