Keystone Building
Why it's listed
Rising four stories on Stolp Island in downtown Aurora, this office building was completed in 1922-23 from designs by George Grant Elmslie, with L. A. Fournier as associate architect. Its facade is brown glazed brick flecked with iron, accented by terra cotta belt courses, large shields and a decorative cornice glazed in brown, green and blue. Shops with private entries line the ground floor, and small office suites fill the upper levels around a central lobby, an original skylight and oak trim. Part of an earlier Aurora Silverplate Company building was incorporated into the northeast portion, a feat the nomination calls a triumph of planning on an irregular lot. It was Elmslie's first commission after leaving his partnership with William G. Purcell. The nomination describes it as the largest private office building he designed and probably the largest Prairie School building of its type, echoing the base, shaft and crown composition favored by Louis Sullivan. It remained largely unaltered and in excellent condition.
Significance in brief: The nomination argues it is the largest private office building designed by George Grant Elmslie and probably the largest Prairie School office building of its type. It was Elmslie's first commission after his split from William G. Purcell and reflects the philosophy of his mentor Louis Sullivan. It is also noted for its skillful incorporation of part of an earlier building on an awkward site.
Machine-generated summary. This summary was generated by a language model from the official nomination document and has not been reviewed line by line by an editor. It may contain errors. Check the source document before relying on any detail. Source: nomination document (PDF) · National Archives catalog entry. NRHP reference 80001370, listed March 18, 1980. Summary generated October 2026 (model claude-sonnet-5-5, prompt v1.0-2026-10-29, confidence high).
Key facts
| Address | 30 S. Stolp Ave., Aurora |
|---|---|
| County | Kane County |
| Listed | March 18, 1980 |
| Reference number | 80001370 |
| Resource type | Building |
| Period of significance | 1900- (specific dates 1922-23) |
| Architect / builder | George Grant Elmslie, Architect; L. A. Fournier, Associate Architect |
| Architectural style | Prairie School office building |
| Areas of significance | Architecture |
| Level of significance | National |
| Status (as stated in the nomination) | Described as in excellent condition, unaltered and occupied, with a superb facade; the only intrusions noted are window air conditioning units and some interior upgrades. |
| Acreage | 0.9 |
| Within district | Stolp Island Historic District |
| Coordinates | 41.75739, -88.31577 (NPS GIS) |
What listing means for this property
For an income-producing building, listing (individually or as a contributing building in a district) is the gateway to the 20% federal rehabilitation tax credit on qualified rehabilitation costs, often stackable with state credits. Work claiming the credit must follow the Secretary of the Interior's Standards and be approved in advance.
Listing does not restrict a private owner acting without federal money or permits; where federal funding or licensing is involved, Section 106 review applies.
General information, not legal or tax advice. Rules change; confirm with your State Historic Preservation Office or a qualified adviser.
Sources and further reading
- National Park Service, National Register of Historic Places database (snapshot May 2026), reference 80001370.
- Nomination form (PDF, National Archives) — catalog entry
- Wikipedia article (used for cross-checking only; text not reproduced here)
- Wikidata Q6398451
- This listing as JSON
Last updated October 2026. Found an error? See the editorial policy for how to report it.