37 William Street, Helensburgh

39 William Street in Helensburgh is an earlier 19th-century single-storey and attic villa with a symmetrical three-bay design, flanked by recessed single-bay pavilions. The building features painted squared and coursed rubble with ashlar dressings, including a base and lintel course, cornice, blocking course, architrave to windows, and pilaster quoins.

The entrance elevation on William Street has a pilastered doorway at the center, which includes a deep-set fanlit panelled door and a half-glazed vestibule door, with a dado rail in the vestibule. There are windows flanking the doorway, a blind window on the return to the right, and a window on the return to the left.

The pavilion to the right on King Street West has a base course, raised margins to the windows, an eaves/lintel course, cornice, blocking course, and quoin strip, topped with a piended grey slate roof. The east elevation features a window at the center, while the north elevation has a three-bay design with a door at the center flanked by windows. A two-storey villa abuts to the west, but it is not included in the listing.

The pavilion to the left on William Street is a mirror image of the right pavilion and has a lean-to porch at the doorway.

The interior has not been seen. The villa features twelve-pane sash and case windows, with plate glass in the pavilions. It has a grey slate roof with ashlar coped skews and corniced squared and coursed sandstone stacks at the gables, along with original cans. There are two slate-hung canted dormers on the east side, which have tripartite pilastered windows with a four-pane sash and case glazing pattern.