- is 68km long, roughly speaking
- is old, in road terms. It predates the 1922 roads list, anyway
- runs between Aldgate in London, and Shoeburyness in Essex
- may be expanded with a crossing into Kent, although this is a contentious topic
Aside from that, its runs through some very interesting places. And that is what this site is all about – the things you can see as you drive along the A13, and the things you may experience if you choose to stop a while and explore.