Below are definitions and photographic illustrations of architectural term beginning with the letter "B".
| Bandage - A strap wrapped around a structure to secure its parts in place. |
| Bargeboard - A decoratively carved board attached to the projecting end of a roof gable. |
| Barrel Roof - A roof or ceiling that has a semi-cylindrical form. |
| Bas-Relief - A carved relief that projects very slightly from the background. |
| Basket-Handle Arch - A round arch with voissoirs that begin to rise at a steep angle, and then quickly change to rising at a shallow angle. |
| Batted Surface - A smooth stone surface finished by scoring long, parallel grooves in it with a mason's chisel. |
| Batten Door - A door made from vertical boards supported by horizontal and diagonal braces. |
| Bay - A vertical section of a wall, roof, or other building part delineated by a support, pier, window, or other architectural object. |
| Beam Ceiling - A ceiling that shows the supporting beams of the floor above. |
| Bed Molding - The molding or series of moldings beneath the corona of a cornice. |
| Bell Arch - A round arch that springs from two large corbels with rounded edges. |
| Belvedere - A building or a part of a building specifically situated to look out on a visually pleasing scene. |
| Beton Brut - Unfinished concrete surface left behind after any forms have been removed. The concrete surface usually retains the impression of the forms, including the wood grain of the form boards. |
| Blind Wall - A wall without any windows or doors. |
| Boasted Surface - A stone finished by chiseling rows of relatively short parallel grooves across its face. |
| Bond - An easily recognized masonry pattern that repeats across a brick or stone wall. The pattern serves the dual purpose of making the wall stronger and more visually interesting. |
| Box Cornice - A hollow cornice made from long, thin boards and nailed to a roof's rafters. |
| Box Gutter - A gutter built into the slope of a roof above the cornice. |
| Broom Finish - A concrete surface with shallow parallel grooves formed by running a stiff-bristled broom or brush over the concrete before it set. |
| Butterfly Roof - A roof that slopes downwards from its eaves. Usually, it looks like an upside-down gable roof. |
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