GPS inspired dinking missions

Nova and I have a new hobby. With the aid of my trusty GPS, and either one or two bikes we've been exploring London.
So far we've discovered that there are canals in north London, that battersea park is big, and that the prime meridian, which is supposed to run through the royal observatory in Greenwich, is actually 84 meters to the east.
I'm turning 27 on Wednesday and going to Amsterdam on Thursday.