Richardsonian Romanesque vs Romanesque
リチャードソニアン・ロマネスク / ロマネスク
Both sit in Historical Styles, so the question is not what they belong to but how they behave. They are reached for with some of the same intent, which is where they get confused.
Richardsonian Romanesque

A late-nineteenth-century American architectural style in which H. H. Richardson recast medieval Romanesque round arches as rough masonry, deep openings, asymmetrical towers and low-spreading masses. Rather than surface decoration, stone weight, shadow depth and broad arches grouping entrances gave churches, libraries, courthouses and stations their public force.
Romanesque

Romanesque art joined pilgrimage and monastic culture to thick walls, round arches, barrel vaults and lucid masses, integrating elongated apocalyptic figures into church portals and capitals.
| Richardsonian Romanesque | Romanesque | |
|---|---|---|
| Era | 1870s–1890s | c. 1000–1150 |
| Family | Historical Styles | Historical Styles |
| Kind | Style | Style |
| Cues | Broad, deeply recessed round arches grouping entrances and windows / Thick rough-faced masonry crossed by bands of contrasting stone / Asymmetrical towers with conical roofs above a low horizontal silhouette / Openings stepping back into the wall, with carving confined to capitals and voussoirs | Thick masonry, small openings and round arches / Barrel or groin vaults carried by heavy piers / Relief filling the semicircular tympanum above a portal / Figures and animals stretched to fit architectural frames |
| Best used for | Giving libraries, schools or civic buildings trust through material weight instead of applied ornament · Gathering a hotel or shop entrance into one large arch to create depth and shelter | Expressing shelter, weight and pilgrimage through massive forms and repeated arches · Separating a medieval reference from Gothic verticality by designing architecture and narrative sculpture together |
| Type | Fit a broad serif title into a voussoir band and do not add ornamental lines finer than the stone joints. | Refer to carved capitals and manuscript initials for short inscriptions and headings only. |
| Composition | Group round arches of different sizes into a low horizontal body, add one tower to one side, and pull openings deep enough to reveal wall thickness. | Repeat round arches across low stable masses and deform figures to fill portals and capitals. |
| Material | Lay large blocks of rough sandstone or granite, changing color or finish only at arch stones and horizontal bands, with dark timber and metal set farther back. | Use rough-cut stone, dark joints and restricted mural color, leaving the weight and hand-cut marks visible. |
| Caution | A round arch alone is not Richardsonian Romanesque. Distinguish it from an ancient or medieval reconstruction through its American civic program, rough massing, asymmetry and deeply recessed openings. | Pointed arches, huge windows and skeletal vertical rise move into Gothic. Preserve the round arch, thick wall and low weight. |