{"nrhp_refnum":"03001287","name":"Exposition Hall, Montgomery County Fairgrounds","other_names":["Exhibition Hall","Agricultural Building","Round House","Mot-356-06"],"category":"building","location":{"address":"Montgomery County Fairgrounds, 1043 S. Main St.","address_restricted":false,"city":"Dayton","county":"Montgomery County","state":"OH","lat":39.74414157600006,"lon":-84.18869000099994,"geom_source":"nps_gis"},"listed_date":"2003-12-10","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Architecture"],"significance_levels":["local"],"summary":{"what_it_is":"A two-story frame octagonal exhibit hall, about 150 feet across, built in 1874 as the centerpiece of the Montgomery County Fairgrounds on South Main Street in Dayton, Ohio.","why_significant":"The nomination argues it is an excellent example of the polygonal exhibit halls built on Ohio fairgrounds in the late 19th century. It is the largest of five surviving eight-sided halls in the state from c. 1871 to 1889. It is also notable for a sophisticated post-tensioned roof framing system that allows a long clear span.","narrative":"Exposition Hall is an eight-sided, two-story frame building about 150 feet in diameter, standing on the highest point of the Montgomery County Fairgrounds in Dayton, Ohio. Built in 1874 to a design by architect Leon Beaver, with Stephen Kemp winning the construction contract for $8,400, it served as the centerpiece of the new fairgrounds and hosted the first Southern Ohio Fair that fall. It has a low hipped roof, a central clerestory, board-and-batten walls and an open central atrium with a cast-iron fountain. Its roof uses post-tensioning with steel cables and turnbuckles, allowing a wide span without interior supports. It is the largest of five surviving octagonal fair halls in Ohio built between about 1871 and 1889, and is recognized for its architecture. Later changes include altered doorways, 1950s renovations and a roof section rebuilt after a 1978 blizzard. Surrounding fair buildings are not part of the listing.","period_of_significance":"1874","architect_builder":"Beaver, Leon (architect); Kemp, Stephen (builder)","architectural_style":"Mid-19th Century: Octagon Mode; Late Victorian: Italianate","criteria":["C"],"status_note":"Described as retaining integrity of design and setting and in good repair; still used as a fairground building, with later alterations including altered doors and a rebuilt roof section after a 1978 blizzard.","vacant_flag":false,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:52:06.917928-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_OH/03001287.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/03001287/76df36a8f4-800.webp","url_1600":"https://nationalhistoricalregister.com/media/03001287/76df36a8f4-1600.webp","licence":"CC BY-SA 3.0","author":"Wdzinc","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Exposition_Hall,_Montgomery_County_Fairgrounds.jpg\" rel=\"noopener\">Wdzinc</a>, <a href=\"https://creativecommons.org/licenses/by-sa/3.0\" rel=\"license noopener\">CC BY-SA 3.0</a>, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Exposition_Hall,_Montgomery_County_Fairgrounds.jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71990416","wikipedia":null,"wikidata":"https://www.wikidata.org/wiki/Q138610184"},"indexable":true,"url":"https://nationalhistoricalregister.com/ohio/montgomery-county/exposition-hall-montgomery-county-fairgrounds-03001287/"}