There will be a talk on First World War training trenches tomorrow.
They were dug in Berkhamsted and Northchurch Commons and stretched for about eight miles.
Most were filled in after the war. The Chilterns Conservation Board has mapped the few that remain.
Volunteer Norman Groves will talk about the mapping process tomorrow at 8pm in Berkhamsted Town Hall. Entry is free for Berkhamsted Citizens Association members and £2 for everyone else.