# Chicago School (シカゴ派の商業建築)

> A language of late-nineteenth-century commercial high-rises in Chicago, making repeated floors and large windows legible on the facade. Chicago windows combine a broad fixed pane with narrower opening panes. Terracotta and concentrated entrance ornament coexist with this regular structure, distinguishing it from the later International Style.

- IndexStyle No.740 — https://indexstyle.org/styles/chicago-school
- Kind: Style · Family: Modern Architecture · Era: 1880s–early 1900s
- Mood: Trust, Technique
- What this family collects: Forms made possible by steel, concrete and glass, together with the answers architects gave about fitting them to a site and a climate, so a universal style sits beside regional dissent.

## Brief inputs

Supply these before production. They are intentionally not invented by the style.

- Deliverable and channel: page, app screen, deck, campaign image, garment, object or space
- Subject and message: what the audience must notice or understand first
- Audience and context: where, when and at what viewing distance it will be encountered
- Format: dimensions, aspect ratio, responsive states, slide count or physical constraints
- Content hierarchy: required copy, data, actions, imagery and legal information
- Production constraints: accessibility, materials, budget, image rights and delivery deadline

## Defining characteristics

- A wide fixed window between two narrower opening windows
- A repeated grid of piers and floor bands
- Projecting window bays and large glazed areas
- Pale terracotta or stone with ornament concentrated near entrances

## Best used for

- Explaining early high-rise architecture through the relationship between windows and structure
- Organising a commercial front through daylight, repetition and a distinct entrance

## Composition recipe

- Typography & lettering: Align signage with entrances and floors rather than covering the facade with a billboard.
- Layout & structure: Repeat a three-part window unit between continuous vertical piers and floor bands.
- Material & texture: Combine broad glass panes, pale ceramic cladding and dark metal, concentrating detail at the street entrance.

## Colour

Read off the reference works below, so a direction rather than a fixed palette.

- Ground: #E4DCCB
- The colour it is remembered by: #83969A
- Text and outlines: #3C4141

## Evidence and rights boundary

- Treat the source of record and reference works below as evidence for understanding the style, not as assets to reproduce.
- The AI interpretation image, when present, is a browsing aid only. It is neither a reference work nor evidence for the definition.
- For a branded design system, translate hierarchy, spacing, colour roles and component logic into an unrelated fictional service. Do not copy logos, proprietary type, icons, product copy, screenshots or exact component geometry.
- For a regional, Indigenous or community-rooted tradition, retain place, authorship and historical context. Do not combine unrelated motifs or reduce the entry to generic ethnic decoration.
- For fashion and subculture, distinguish documentary context from a costume prompt; use fictional adults and avoid real labels, public figures and caricature.
- Record the rights status and intended use of every supplied image, typeface, logo and quotation before production.

## Translate it by medium

The rules below preserve the visual grammar without copying a historical artefact literally.

### Web and app

- Page structure: translate “Repeat a three-part window unit between continuous vertical piers and floor bands.” into the hero, section rhythm and information hierarchy.
- Type system: use “Align signage with entrances and floors rather than covering the facade with a billboard.” for display moments and short labels. Keep body copy, navigation, forms and status text in a highly legible companion when the display treatment reduces clarity.
- Components and imagery: carry “Combine broad glass panes, pale ceramic cladding and dark metal, concentrating detail at the street entrance.” through image treatment, borders, dividers, cards and selected surfaces; do not decorate every component equally.
- Tokens: begin with #E4DCCB as the ground, #83969A as the memorable colour, and #3C4141 for text, outlines and high-contrast detail. Assign colours by semantic role before tuning individual components.
- Presentation: render the screen itself as the design artefact. Add a phone, browser chrome or perspective mockup only when the deliverable explicitly asks for one.
- Responsive behaviour: preserve hierarchy, alignment logic and the dominant cue when columns collapse; do not reproduce a desktop composition by merely shrinking it.
- Usability gate: keyboard focus, action labels, contrast, zoom and reduced-motion behaviour remain explicit even when the historical style did not account for them.

### Slides and decks

- Title slide: express one idea with the strongest scale, alignment or framing move from “Repeat a three-part window unit between continuous vertical piers and floor bands.”.
- Content slides: keep the reading layer quieter than the title layer. Use one dominant characteristic per slide and repeat the same grid, margins and type roles across the deck.
- Images and surfaces: art-direct crops, masks, rules and backgrounds with “Combine broad glass panes, pale ceramic cladding and dark metal, concentrating detail at the street entrance.” rather than adding unrelated decoration.
- Charts and diagrams: use #E4DCCB as the ground, #83969A as the memorable colour, and #3C4141 for text, outlines and high-contrast detail; preserve labels and numerical contrast before stylistic treatment.
- Presentation: deliver a flat slide canvas by default. A photographed screen, laptop or conference room is a different deliverable and must be requested explicitly.
- Sequence: alternate emphatic slides with quiet explanatory slides so the style has rhythm instead of becoming constant noise.

### Image generation and art direction

- Subject: choose one concrete subject that serves one of the uses above; the style is the treatment, not the subject.
- Composition: build the frame from “Repeat a three-part window unit between continuous vertical piers and floor bands.”. Make the focal hierarchy readable before adding texture.
- Lettering and graphic marks: follow “Align signage with entrances and floors rather than covering the facade with a billboard.”. If text is not essential, omit it; if it is essential, use short neutral wording and reject illegible pseudo-text.
- Surface, light and finish: interpret “Combine broad glass panes, pale ceramic cladding and dark metal, concentrating detail at the street entrance.” as material, texture, edge quality, depth and lighting rather than as a generic filter.
- Effect discipline: gradients, bloom, glass, chrome, heavy shadows, grain and distressed paper are off by default unless the material direction names or clearly requires them.
- Cliché test: remove the most obvious period prop or motif. The style should still read through composition, type, colour relation and material behaviour.
- Set direction: make a clear establishing composition, a changed crop or viewpoint, a material/detail study, and a reduced alternate. Keep the visual grammar stable while changing the framing.
- Ready-to-run prompt: https://indexstyle.org/styles/chicago-school/prompt.txt

### Styling, objects and spaces

- Silhouette and proportion: translate “Repeat a three-part window unit between continuous vertical piers and floor bands.” into the distribution of volume, balance, symmetry or asymmetry.
- Materials and finish: start from “Combine broad glass panes, pale ceramic cladding and dark metal, concentrating detail at the street entrance.”; choose real materials whose behaviour supports the style instead of printing a motif onto an unrelated surface.
- Graphic detail: apply “Align signage with entrances and floors rather than covering the facade with a billboard.” only where lettering, labels, trims or wayfinding have a reason to exist.
- Palette: use #E4DCCB as the ground, #83969A as the memorable colour, and #3C4141 for text, outlines and high-contrast detail. Let one role dominate, one support and one provide legibility or edge definition.
- Edit: carry two or three defining characteristics strongly. Avoid turning every characteristic into a literal prop or costume reference.

## What to avoid

Not every glazed grid is Chicago School. Keep the early commercial tradition distinct from the later Second Chicago School and from the Chicago Imagists in painting.

## Application checklist

Work through this before calling a piece an application of this style.

- [ ] The deliverable, subject, audience, format and content priority are explicit
- [ ] One characteristic is dominant and at least two others support it
- [ ] Visible in the piece: A wide fixed window between two narrower opening windows
- [ ] Visible in the piece: A repeated grid of piers and floor bands
- [ ] Visible in the piece: Projecting window bays and large glazed areas
- [ ] Visible in the piece: Pale terracotta or stone with ornament concentrated near entrances
- [ ] The layout follows: Repeat a three-part window unit between continuous vertical piers and floor bands.
- [ ] The lettering follows: Align signage with entrances and floors rather than covering the facade with a billboard.
- [ ] The material and surface follow: Combine broad glass panes, pale ceramic cladding and dark metal, concentrating detail at the street entrance.
- [ ] The colour relation holds: #E4DCCB as ground, #83969A carrying the style, #3C4141 for text and outlines
- [ ] The result still works without the decorative layer: hierarchy, reading order and primary action remain clear
- [ ] Responsive, accessibility or physical-production constraints have been checked for the chosen medium
- [ ] No AI interpretation image has been used as evidence or copied as a visual reference
- [ ] Logos, proprietary type, exact interface geometry and existing artwork compositions have been excluded unless separately licensed
- [ ] Community, regional or subcultural context has been preserved where it is part of the style
- [ ] At least one reference work below has been studied directly
- [ ] The caution above ("What to avoid") has been addressed

## Related styles

- **International Style (インターナショナル・スタイル)** — Strips ornament and aims at a universal architectural language crossing borders: the box, the free plan, steel, concrete and glass. → https://indexstyle.org/styles/international-style
- **Richardsonian Romanesque (リチャードソニアン・ロマネスク)** — 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. → https://indexstyle.org/styles/richardsonian-romanesque

## Compose it with something else

The dictionary can put this entry in a structural role and another in an accent role, and report where the two fight: https://indexstyle.org/compose?ids=chicago-school+international-style

## Further study

- Reliance Building — Charles B. Atwood / D. H. Burnham & Co.
- Marquette Building — Holabird & Roche
- Sullivan Center — Louis Sullivan

## Reference works

- Reliance Building, Chicago — photo: Jay Carriker — Wikimedia Commons / CC BY-SA 2.5 — https://commons.wikimedia.org/wiki/File:Reliance%20Building%2C%20Chicago%2C%20Illinois%20(November%202005).jpg
- Reliance Building — HABS measured floor plans (Library of Congress) — Wikimedia Commons / Public domain — https://commons.wikimedia.org/wiki/File:Reliance%20Building%2C%2032%20North%20State%20Street%2C%20Chicago%2C%20Cook%20County%2C%20IL%20HABS%20ILL%2C16-CHIG%2C30-%20(sheet%202%20of%204).png

## Source of record

- Chicago Architecture Center — Chicago Window / Reliance Building — https://www.architecture.org/online-resources/architecture-encyclopedia/chicago-window

## Machine surfaces

- JSON: https://indexstyle.org/api/styles/chicago-school
- Image-generation prompt (legally clean): https://indexstyle.org/styles/chicago-school/prompt.txt
- MCP: https://indexstyle.org/mcp (tools: search_styles, get_style, compare_styles, compose_styles, find_related_styles; prompts: image-prompt, apply-style)