One of my favourite things to do on the weekends is wander around the City, the central business district of London. It's mostly offices, plus some landmarks like St. Paul's Cathedral and the Bank of England. Because it's a place where people tend to work rather than live, on the weekends it can get very quiet and peaceful, especially in the side streets.
Last weekend I ran across this stunning building right near St. Paul's. From the Latin inscription along the top, it looks like it might have had some function related to the Cathedral in the past. Now it's the local youth hostel!