I have a few regular routes, each of which takes me ten or fifteen miles and allows me to fit in a quick ride before dinner without having to think too much about where to go. Because I regularly ride the same routes, they are quite familiar. On each I have picked out little landmarks that mark progress - things like a nice bridge over the railway, or a view of the river.
On one of them there is a short section of country lane which is a most peculiar ride. The surface is crossed by ripples, with the peaks at just the wrong distance apart. So when the back wheel is in a dip, the front wheel is on a crest, and vice versa. The bike pitches backwards and forwards, as though it is on oval wheels. It's not a very pleasant sensation, but it is impossible to ignore, and it has become one of my markers as I progress round that particular ride.
On another of my regular routes there has been a trench down the road for the last few weeks while they do something important to the pipes (or so they say - I prefer to imagine them burying their loot). They have just finished one section, and moved on to the next leaving a new section of road surface. Cunningly, they've recreated the rippled effect from the country lane, almost to perfection. Now I have a way of marking progress around both routes.
I just hope the idea doesn't catch on.