A lewis is one of a category of lifting devices used by stonemasons to lift large stones into place with a crane, chain block, or winch. It is inserted into a specially prepared hole, or seating, in the top of a stone, preferably above its centre of mass. It works by applying principles of the lever and utilises the weight of the stone to act on the long lever-arms, which in turn results in a very high reaction force and friction where the short lever-arms make contact with the stone inside the hole and thereby prevents slipping.

Stonemasonry or stonecraft is the creation of buildings, structures, and sculpture using stone as the primary material. Stonemasonry is the craft of shaping and arranging stones, often together with mortar and even the ancient lime mortar, to wall or cover formed structures.