John Hammond Jr.'s Medieval Castle of Invention and Séances
80 Hesperus Ave, Gloucester, MA 01930
Research updated June 2026
Age
All Ages
Cost
$$
Weekdays (Mon-Thu, excluding holidays): Adults/Teens $20, Seniors (65+) $15, Children (5-12) $10, Children 4 and under free (ticket required). Weekends/Holidays (Fri-Sun & holidays): Adults/Teens $25, Seniors $17, Children 5-12 $10, Children 4 and under free. Members free for daytime tours.
Access
Limited Access
Six levels connected by over 160 steps; not wheelchair accessible. Service dogs permitted. Contact museum for accommodation alternatives.
Equipment
Photos OK
Est. 1929 · Hammond Invention Legacy · Medieval Collections · Spiritualism Research History · Coastal Massachusetts Architecture
John Hays Hammond Jr. graduated from Yale in 1910 and spent the following decades accumulating over 400 patents, working primarily in radio control and remote guidance technology — his work in wireless became foundational for modern guided missile systems. He was closely associated with Thomas Edison and Alexander Graham Bell, both of whom visited the castle.
Hammond purchased the property on Hesperus Avenue in Gloucester and constructed the castle between 1926 and 1929, drawing on architectural references from European medieval and Renaissance structures he had studied during travels abroad. The resulting building was neither reproduction nor pastiche: it was a functional private residence and working laboratory that happened to incorporate a 100-foot great hall, an 8,200-pipe organ, and embedded medieval stonework alongside modern research equipment.
The collection includes Roman stonework, medieval furnishings, Renaissance artifacts, and a 16th-century carved wooden fireplace surround transported from France. After Hammond's death in 1965, the castle passed through several ownership arrangements before being established as a nonprofit museum.
The museum operates at 80 Hesperus Avenue, Gloucester, Massachusetts 01930, open daily from 9:00 AM to 3:30 PM. It has been recognized as a STEAM education resource — science, technology, engineering, art, and mathematics — owing to Hammond's breadth of work and the building's dual character as residence and laboratory.
Sources
The Hammonds' interest in spiritualism was not peripheral to their lives at the castle — it was central to how they used the Great Hall. John and Irene regularly invited prominent mediums for séances, and in the early 1950s, Hammond conducted experiments in telepathy using a Faraday cage in collaboration with the psychic Eileen J. Garrett. Irene produced extensive astrological writing under a pen name whose identity she kept private.
This documented history distinguishes Hammond Castle from locations where paranormal reputation is assigned retroactively. The Hammonds were attempting, by whatever methods available to them, to actually contact or demonstrate something. Whether those attempts succeeded is a separate question from the fact that they were conducted sincerely and systematically.
Staff and visitors have reported whispers in the Great Hall and along the castle corridors, shadow movement on walls in rooms that have no corresponding light source, and cold that arrives and departs without explanation. These reports are consistent across different periods of the castle's history as a museum.
The Spiritualism Tours by Candlelight, offered on Thursday evenings from July through October, are the museum's acknowledgment of this history — tours focused specifically on the Hammond household's documented spiritual practices, presented in the rooms where those practices occurred.
Notable Entities
Explore the medieval-style castle that inventor John Hays Hammond Jr. built between 1926 and 1929 as his residence and laboratory. The Great Hall — where Hammond and his wife Irene held séances with prominent mediums — anchors the tour. Guided tours run 35-40 minutes; self-guided access allows more time in the six-level structure.
A 55-minute evening specialty tour focused on Hammond's experiments in telepathy, séance practices, and the Hammonds' documented attempts to contact spirits using Faraday cages. The tour highlights Irene Hammond's astrological writings and the castle's history as a genuine site of spiritualist investigation, not theatrical performance.
Every HauntBound history is researched from documented sources. We clearly separate verified historical fact from paranormal folklore.
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