This aptly-named puzzle represents the 25th numbered work of Robert Yarger and, along with the non-numbered work, includes the 1000th puzzle crafted by him. The Milestone Puzzle is really a book within a cage within a cage. (The inner cage appears below.)
Once both cages are negotiated (I absolutely LOVE the overall mechanical look of the work ... no one does it like Robert), a complete retrospective of Robert's work awaits, resplendent with full-color photos and accompanying descriptive text. Oh, and there are puzzles within the book too! Truly a milestone!