Round House, an octagonal building Wyeth had constructed; in which Betsy Wyeth now archives her husband’s works. “One if by land, and two if by sea” references Henry Wadsworth Longfellow's poem, "Paul Revere's Ride."
https://www.pinterest.com/pin/260786634660266795/
So if I understand correctly, this building has nothing whatsoever to do with Paul Revere's Ride, or related architecture. Interesting building, tho!