{"nrhp_refnum":"81000547","name":"Lock Ridge Furnance Complex","other_names":["Lock Ridge Furnace Museum"],"category":"building","location":{"address":"Franklin and Church Sts.","address_restricted":false,"city":"Alburtis","county":"Lehigh County","state":"PA","lat":40.50880778650003,"lon":-75.59382925497685,"geom_source":"nps_gis"},"listed_date":"1981-09-11","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Industry"],"significance_levels":["local"],"summary":{"what_it_is":"The Lock Ridge Furnace Complex is an iron-making site at Alburtis in Lehigh County, Pennsylvania, made up of stone and brick furnace buildings, engine and cast rooms, a weighmaster's house and an oil house, with ruins of other structures around them. It was converted into a county park and museum.","why_significant":"The nomination argues the complex illustrates the nineteenth-century shift to anthracite-fueled, hot-blast iron making that drove the anthracite iron industry of the Lehigh Valley. Furnace No. 7 was built in 1868 by the Thomas Iron Co., which kept it operating until 1921. The document also states that it is the only remaining group of structures from the furnaces operating in 1876 in central and eastern Pennsylvania, apart from a Scranton museum site.","narrative":"Alburtis, in Lehigh County, Pennsylvania, holds the remains of an anthracite iron works built in 1868 by the Thomas Iron Company. Furnace No. 7 is a square stone base about thirty feet high, topped by a brick cone, and it sits beside an engine room, a cast room and a weighmaster's house. The works used anthracite coal, a hot blast and a steam engine, a process that replaced charcoal and water-powered bellows and that helped drive the iron industry of the Lehigh Valley. The Thomas Iron Company operated the furnaces until December 1921, after which the metal was sold for scrap and the stone buildings were left to decay. Lehigh County acquired the ruins for a park and museum in the early 1970s, and restoration work was completed in 1975. The site is significant for its link to the industrial change that supplied iron for the country's railroads and machinery.","period_of_significance":"1800-1899","architect_builder":null,"architectural_style":"Pennsylvania vernacular (weighmaster's house); Victorian Gothic lines (complex, as described)","criteria":[],"status_note":"Converted into a museum and park by Lehigh County in the 1970s after restoration work completed in 1975","vacant_flag":null,"machine_generated":true,"model":"claude-haiku-5-5","prompt_version":"v1.1-2026-10-29","generated_at":"2026-10-29 17:11:32.740096-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/lz/electronic-records/rg-079/NPS_PA/81000547.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/81000547/87cd8eef6e-800.webp","url_1600":"https://nationalhistoricalregister.com/media/81000547/87cd8eef6e-1600.webp","licence":"CC BY-SA 3.0","author":"PattiParker","credit_html":"<a href=\"https://commons.wikimedia.org/wiki/File:Lock_Ridge_Furnace_Complex.JPG\" rel=\"noopener\">PattiParker</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:Lock_Ridge_Furnace_Complex.JPG"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/71994459","wikipedia":"https://en.wikipedia.org/wiki/Lock_Ridge_Furnace_Complex","wikidata":"https://www.wikidata.org/wiki/Q139744519"},"indexable":true,"url":"https://nationalhistoricalregister.com/pennsylvania/lehigh-county/lock-ridge-furnance-complex-81000547/"}