a Johnston Historical Society newsletter from September, 1989 (Vol. V,
No. 1) - not yet online, includes an excerpt from this publication, if
you can find a copy of the original book:
CAPTAIN ARTHUR FENNER
(excerpt)
_History of the Fenner Family, _compiled by Lucinda T. Fenner.
Plainwell, Michigan: [privately printed], 1908.
which mentions "Fenner Castle":
"It is estimated that he held the title to over 500 acres of land. In
1662 he built a house on a piece of land which he owned, about four
miles from Providence. This was burned by the Indians in 1676, after
which he built on the same site a house which was known for generations
as Fenner Castle. Nothing is left of the house as originally built. "
the newsletter's editor also references a pamphlet "Fenner Castle"
(dated March 30, 1931) in the Old Stone Bank series on Rhode Island
history.