I am recalling a trip I took with my husband to Britain, one of many. I told him we were on one of the oldest roads he had ever walked on. It was a ridgeway.

Being American, he responded with "Wouldn't the road be down in the valley?"

Me: In the mud?

It's a reminder that roads take all kinds of forms. We often think of Rome as the great road builders, but roads are an essential part of life.

Roads are one of the few items of technology we didn't so much invent as inherit. Badgers, for example, have routes so set that they have had to build tunnels for them so they wouldn't walk straight across our roads. Deer have roads. Lots of animals have roads.

Only humans build roads. Which are key to our life.

So, lets talk about a whole bunch of different types of roads.