Bead: a small convex moulding; often decorated with Bead and Spool ornament.
Bead and Spool: an ornamental device of small halved spheres, alternating with halved spools; used on small convex mouldings.
Beauty: as applied to Architecture, those qualities in a building that stimulate and gratify the æsthetic sense. They result from the architect having created an Organic structure according to the principles of Fitness, Unity, Proportion, Harmony, and Rhythm (see these terms).
Bel Étage: French term for the principal story of a building. Compare Italian, Piano Nobile.
Belfry: specifically, the part of a tower in which the bells are hung; hence, sometimes, the whole tower.
Bema: a raised platform, reserved for the clergy in Early Christian churches.
Blind Arcades: See Arcade.
Bond: the method of laying bricks or stones to bind the masonry. In English Bond, the courses are composed alternately of Headers and Stretchers (which see); in Flemish Bond the Headers and Stretchers are laid alternately in each Course (which see).
Boss: ornamental projection at the intersection of the ribs of vaults and ceilings.
Bow-window: See Bay-window.