'The Treehouse Book'

Skyhorse Publishing, $19.95:

Although the treehouse is often associated with a backyard refuge for children, author Candida Collins calls the treehouse "one of the earliest forms of human protection." And, as this book makes amply clear, treehouses are no longer just for children. Indeed, since the 1990s treehouses have been enjoying a resurgence in popularity. In this quirky book, Collins profiles various types of treehouses around the world. They include a high-tech hideaway (it features an advanced security system) on a private estate in Athens, Greece, and a treehouse set inside a secret garden, complete with a spiral staircase, that is more like a fairy-tale castle. Another treehouse functions as an inspirational home office, a short "commute" from the main house across a rope bridge. Collins also includes a section on building a treehouse. Depending on your budget and skills, you can either build it yourself or commission a professional.