Mike Salter, trading as Folly Publications, has produced this series of books about medieval castles, parish churches, monastic sites and long distance walking trails in various parts of England, Wales, Scotland, Ireland, the Isle of Man, and the Channel Islands. His latest book, Medieval Walled Towns, was published in March 2013.
The books contain many black and white photographs of castles and churches with many plans reproduced to a set of common scales to allow comparisons of buildings of similar types (e.g. all churches, keeps, tower houses, gatehouses, etc. at 1:400, and courtyard castles mostly at 1:800, earthworks and large sites at 1:2000).