A Newport mansion is being restored with a staircase technique dating to the 1500s; instead of modern exposed fasteners, craftsmen lock the wooden steps together with mortises and wedges

• The project’s heart is a dramatic helical staircase with laminated curved stringers and mortised-and-wedged treads and risers.
• As per reports, the technique originated in the construction of European staircases in the late 1500s, when wealthy homes and castles had elaborate staircases.
• A stairway goes up to nowhere in a woodshop.