{"nrhp_refnum":"99000498","name":"Watertown Arsenal Historic District","other_names":["Army Materials Technology Laboratory"],"category":"district","location":{"address":"Arsenal St.","address_restricted":false,"city":"Watertown","county":"Middlesex County","state":"MA","lat":42.361762500000026,"lon":-71.16455212700316,"geom_source":"nps_gis"},"listed_date":"1999-05-14","is_nhl":false,"nhl_designated_date":null,"areas_of_significance":["Architecture","Engineering","Industry","Invention","Landscape Architecture","Military"],"significance_levels":["national"],"summary":{"what_it_is":"A 45-acre U.S. Army industrial, research and residential complex on the south side of Arsenal Street in Watertown, Massachusetts, also known as the Army Materials Technology Laboratory. It holds masonry buildings built between the mid-19th and mid-20th centuries and an Olmsted-designed landscape, on part of an arsenal established in 1816.","why_significant":"The district preserves a group of buildings, structures and landscape features that were integral to the Watertown Arsenal's work from 1816 to 1947. Its gun carriage manufacturing complex illustrates changes in industrial design in the second half of the nineteenth century. Its differentiated zones for industry, research, administration and housing are linked by shared roads, architecture and landscaping.","narrative":"Occupying 45 acres along Arsenal Street in Watertown, this district is the surviving core of the Watertown Arsenal, an Army ordnance depot founded in 1816 and later home to the Army Materials Technology Laboratory. Its red brick buildings, with spare classically inspired designs from different periods, include 15 contributing buildings, three structures, a site and an object. A cluster of four long gable-roofed buildings formed the gun carriage manufacturing complex, dating from 1851 to 1894. Research laboratories occupy the western part, including a converted 1922 piano factory. Near the entrance drive, the Italianate Commanding Officer's Quarters and the Colonial Revival Administration Building sit within a landscape designed by the Olmsted firm. The district is surrounded by brick posts and wrought iron fencing. Land to the east, once part of the arsenal, was turned over to the town in 1968 and is outside the district. Contributing resources relate to the Arsenal's activities between 1816 and 1947, which marks its period of significance.","period_of_significance":"1816-1947","architect_builder":"Monks & Johnson (Boston architectural and engineering firm, for 1917 changes to Building 43); Olmsted firm (landscape)","architectural_style":"Mid 19th Century; Late Victorian; Early 20th Century Industrial, No Style","criteria":[],"status_note":"Current functions listed as defense military facility and vacant/not in use; the text also says the northeast area continues to be used by the General Services Administration and the Reactor (Building 100) was demolished in 1993.","vacant_flag":null,"machine_generated":true,"model":"claude-sonnet-5-5","prompt_version":"v1.0-2026-10-29","generated_at":"2026-10-29 02:13:03.500435-05","source_pdf":"https://s3.amazonaws.com/NARAprodstorage/opastorage/live/17/7959/63795917/content/electronic-records/rg-079/NPS_MA/99000498.pdf"},"photo":{"url_800":"https://nationalhistoricalregister.com/media/99000498/2b195a8995-800.webp","url_1600":"https://nationalhistoricalregister.com/media/99000498/2b195a8995-1600.webp","licence":"Public domain","author":"Jack E. Boucher.","credit_html":"Jack E. Boucher., Public domain, via Wikimedia Commons","source_page":"https://commons.wikimedia.org/wiki/File:Watertown_Arsenal,_building_-71_(Watertown,_MA).jpg"},"district":null,"sources":{"nps_snapshot_date":"2026-05-22","nara_catalog":"https://catalog.archives.gov/id/63795917","wikipedia":"https://en.wikipedia.org/wiki/Watertown_Arsenal","wikidata":"https://www.wikidata.org/wiki/Q2864383"},"indexable":true,"url":"https://nationalhistoricalregister.com/massachusetts/middlesex-county/watertown-arsenal-historic-district-99000498/"}