pyrgologist n.

"one versed in the structure and history of towers," 1877, from Greek pyrgos "a tower, wall-tower, siege-tower; highest point of a building" (a technical term in architecture, of uncertain origin, according to Beekes "clearly Pre-Greek") + -ologist. It seems to have been used once, in The Athenaeum of Aug. 18, 1877, and then forgotten except in dictionaries.