We have a soft spot for sundials, since they have no moving parts (except for the shadow) and are powered by solar energy. And we also enjoy doing themed walks. So when we saw that there is a Thames Sundial Walk in London, we just had to do the walk.
Oddly enough, we accidentally stumbled across an interesting set of sundials as we were walking to the start of the sundial trail. At Seven Dials there is a tall column in the centre of a roundabout, and it is adorned by 6 (not 7) small sundials. They all face in different directions, so each one tells the time for a different range of hours.