Credits

Credits

Nothing here is original data. The index is public records, put side by side. These are the records, the references the method rests on, the software it runs on, and the people whose work set it going.

The idea

Louis Joyner, Architect, Columbus, Indiana, who inspired the idea: that the question of how a town of fifty thousand came to hold so much recognised architecture deserves a fair, public answer, measured against every other city.

Landmark Columbus Foundation, whose site inspired the look of this one: Futura, slate, one blue and one red. Credit to Jamie Goldsborough, the foundation's creative director, for that design.

Jonathan Nesci, designer, Columbus, Indiana, who helped refine the idea and the style, and whose collaborative practice, w/, work made with the region's makers, is the model for how this index should be built: with others.

Jonathan Nesci and Rachel, who have tested the site as it was being built and said plainly what did not work. Much of what changed between versions started with them.

Build Fractal, which built it. The American Institute of Architects' 1991 ranking of U.S. cities by architecture, which named Columbus sixth and was never repeated, is the list this index was made to replace with something reproducible.

Data

National Register of Historic Places
National Park Service. The listed-properties spreadsheet is the roster: every listing, its reference number, category, level of significance and areas of significance. The National Historic Landmarks list is the same service's. Public domain.
NRHP map service
National Park Service. A coordinate for each listing and, for districts, the count of contributing buildings. The coordinate is what places a listing inside a city. Public domain.
NPGallery
National Park Service. Nomination documents: the forms and narratives that name a property's style, period and architect, for about one listing in seven. The index archives each one and reads the text. Public domain.
TIGER/Line and the Gazetteer
U.S. Census Bureau. The legal boundary of every place, and its land area in square miles. Public domain.
American Community Survey
U.S. Census Bureau. Population (table B01003) and housing units (B25001), 5-year estimates, one vintage for every place. The Bureau's batch geocoder fills coordinate gaps. Public domain.
Wikidata, Wikipedia and Wikimedia Commons
Wikimedia Foundation and volunteers. Style, architect, build year and the photograph where a volunteer has recorded them; one sentence from each article; article text read for listings whose nomination names no style. Wikidata is CC0; Wikipedia text is CC BY-SA 4.0 and is quoted one sentence at a time with a link to its article; photographs are shown under their own licences with the photographer's name where Commons records one.
Register Atlas
Open data at registeratlas.com, CC0. Build year, style and architect, cross-checked against the above. Its styles are drawn from Wikidata, so a style resting on Register Atlas alone counts as inferred, not official.
National Archives Catalog
National Archives and Records Administration. The scanned nomination behind most listings, National Historic Landmark nominations, and the source cited for each entry in the corrections file. Public domain.
State historic preservation offices
Nominations the national sources lack, read for the index: the Virginia Department of Historic Resources (not subject to copyright), the Missouri, Illinois and Tennessee State Historic Preservation Offices, the North Carolina State Historic Preservation Office and the Texas Historical Commission (Texas Historic Sites Atlas). North Carolina and Texas allow non-commercial use with credit only, so their copies are read for search and never quoted, shown or linked; each listing links to the National Park Service record.
Map tiles
OpenFreeMap, from OpenMapTiles and © OpenStreetMap contributors (ODbL).

Method references

Size classes
The Census Bureau's standard size-of-place classes, so cities compete with cities of their own size.
Style vocabulary
National Register Bulletin 16A, How to Complete the National Register Registration Form (National Park Service, 1997), whose architectural classification is the top of the tree, and Virginia Savage McAlester, A Field Guide to American Houses (second edition, 2013), for the styles, variants and periods beneath it.
Adjusted rate
R. J. Marshall, "Mapping disease and mortality rates using empirical Bayes estimators," Applied Statistics 40 (1991): the Poisson-gamma shrinkage that keeps a town with three listings from topping a table on luck.

Software

MapLibre GL JS (BSD-3) draws the city maps. DuckDB (MIT) and its spatial extension do the joins. The typeface is Jost by Owen Earl (SIL Open Font License), a free cousin of Futura, which it stands in for. jsPDF (MIT) makes the tour and city fact-sheet PDFs in the browser. The pipeline is Python with DuckDB, NumPy and openpyxl, and the site, its document archive and its search run on Amazon Web Services. The nomination texts were read for style by Claude (Haiku 4.5, and Haiku 5.5 from Idaho onward) inside Claude Code, and the site was built with Claude Code; every model-read tag is marked unverified until a person checks it.

Search in your own words uses Nomic Embed Text v1.5 (Apache 2.0) to match a sentence to the nomination texts, with the vectors kept in Amazon S3 Vectors, and Claude Haiku 4.5 on Amazon Bedrock to read the sentence into filters you can see. Photos and plans uses Nomic Embed Multimodal 7B (Apache 2.0), built on Alibaba's Qwen2.5-VL (Apache 2.0): the pages were indexed with vLLM (Apache 2.0) and searches are answered with llama.cpp (MIT). Building facts are read from the nominations by Claude Haiku 4.5 on Amazon Bedrock and checked by a stronger Claude model against the page each fact came from.

Work we drew on

Ideas this index uses from other people's open work. None of their code is copied here; each line says what we took.

Corrections

If a source is missing, misattributed or wrongly licensed here, say so and it will be fixed. The same goes for any number on the site: how the index works explains where each one comes from.