I spent last weekend in Lancaster. While I was there I took a walk into Williamson Park so I could go and take some photographs of a pretty neat sundial they've got there.
When someone mentions "sundial" most people probably think of the more "traditional" kind of sundial that has a fixed gnomon. The Lancaster Sundial is a little different in that it's an analemmatic sundial and you play the part of the gnomon.
In the middle of the dial is an analemma. To tell the time, and to take the equation of time into account, you pick a spot to stand on depending on the date and then use your shadow to figure out the time (adding an hour if needed depending on daylight saving time).
You can see more images of the sundial in my album of photographs of Lancaster.