An 1879 Fort Collins sandstone home where the original owner died with 50 times the lethal dose of arsenic in his system; his wife remarried 12 days later. Now a public history museum with weekend tours.
328 W Mountain Ave, Fort Collins, CO 80521
Research updated June 2026
Age
All Ages
Cost
$
Free or small suggested donation for weekend tours; see poudrelandmarks.org for details
Access
Limited Access
Victorian-era home; stairs throughout; limited accessibility
Equipment
Photos OK
Est. 1879 · Franklin Avery — civil engineer and Fort Collins founder · National Register of Historic Places (1974) · Outstanding example of Victorian-era Front Range sandstone construction · Site of investigated arsenic poisoning death
Franklin Avery arrived in Fort Collins in 1872 and spent decades helping shape the city's physical layout. Trained as a civil engineer, he surveyed streets, platted subdivisions, and contributed to the early infrastructure of one of Colorado's largest Front Range cities. The sandstone house he built in 1879 at 328 W Mountain Avenue remains one of the finest examples of Victorian residential architecture in Fort Collins.
The house passed through the Avery family for generations. The most troubling chapter involves William Avery, whose death was found to involve arsenic levels measured at fifty times a lethal dose. Just twelve days after William died, his wife Mary married Frank Millington, a business partner. The circumstances of William's death were investigated at the time, though the historical record on the legal outcome is unclear in published sources. The rapid remarriage has made this one of the most frequently discussed episodes in Fort Collins' local history.
The property was added to the National Register of Historic Places in 1974. Poudre Landmarks Foundation now operates the house as a museum open for weekend afternoon tours, interpreting the Avery family's role in Fort Collins' founding era.
Sources
Paranormal reports at the Avery House center on the upper floor, particularly the bedroom where the arsenic death occurred. Visitors on weekend tours and staff who spend time alone in the building have described a sense of presence and unexplained sensory disturbances in that room. Two Fort Collins regional publications have documented these accounts as part of broader surveys of the city's haunted sites.
The case for a haunting here rests partly on the specificity of the dark history: a death with arsenic at fifty times the lethal dose, and a widow's remarriage twelve days later, combine to give the house a verifiable human tragedy rather than generic legend. Whether that history has any bearing on the reported activity is beyond the published record, but the house's documented forensic past is the context through which residents and visitors interpret the reports.
No formal paranormal investigation findings are available in the published record. The house's status as a National Register site with public weekend tours makes it one of Fort Collins' most accessible dark-tourism stops.
Notable Entities
Tour the 1879 sandstone home of Franklin Avery, one of Fort Collins' founders. Guides cover the architecture, Avery's role in surveying and developing the city, and the dark chapter of William Avery's arsenic death in the house.
Every HauntBound history is researched from documented sources. We clearly separate verified historical fact from paranormal folklore.
Indianapolis, IN
Hannah House is an 1858 Italianate mansion at 3801 Madison Avenue on the south side of Indianapolis, built by Alexander Hannah, an Indiana businessman who returned wealthy from the California Gold Rush. The property is listed on the National Register of Historic Places.
Charles City, VA
Benjamin Harrison IV built the current mansion at Berkeley Plantation in 1726, making it the oldest three-story brick structure in Virginia. The plantation became the birthplace of President William Henry Harrison in 1773 and the ancestral seat of a family that produced a signer of the Declaration of Independence and two U.S. Presidents. During the Civil War, General McClellan used the mansion as his headquarters and the cellar held Confederate prisoners.
Macon, GA
Built between 1855 and 1859 for businessman William Butler Johnston at a cost of approximately $100,000, the Italian Renaissance Revival mansion at 934 Georgia Avenue has been called the 'Palace of the South' and is a National Historic Landmark. The Felton family held it through the Civil War period; Confederate general Henry Gray Felton occupied it during the war. The Hay family acquired the house in 1926 and donated it to The Georgia Trust for Historic Preservation in 1977.