We might never have known of Effingham’s former tithe barn had it not been for a single indication of it on a plan accompanying a contract of sale made in 1803. In this article we explain the history and application of tithes in order to set this finding in context, and also discuss some of the tithe records for Effingham pertaining to the approximate period when the plan was drawn. The article finishes by comparing the tithe barn’s site as shown on that plan with how the site appears today.