When is a threshold a portal? What is a sallyport? How many ways are there to cross a wall, a fence, or a river? What is a kissing gate? Are there gateways to other worlds? In this beautiful book, packed with rare antique illustrations and original drawings by artist Miles Thistlethwaite, author Philippa Lewis explores the fascinating world of liminal boundaries and the inexhaustible variety of ways in which we cross them.