Build a working model of the Roman Arch and learn why this structure is so strong. This clever and attractive puzzle is also an intriguing lab in force and geometry. Try building it without the template first - it's not as easy as it looks! Build it on a flat surface and then carefully raise it up. The kit includes: 23 pine blocks in 6 unique shapes; predrilled buttress in 3 sections; hardware; instructions with historical background and full-scale template