91, 93 Sinclair Street, Helensburgh

91 and 93 Sinclair Street in Helensburgh is an earlier 19th-century, two-storey, three-bay flatted villa featuring classical details. The building is constructed of cream rubble, painted on the north and south elevations, with ashlar margins. It has a base course, raised margins around the windows, pilaster-quoins, and a cornice.

On the south elevation, there is a corniced doorway at the center with a modern fanlit door. Flanking this are windows at the ground level, and there are three regular windows on the first floor. The east elevation facing Sinclair Street has a window at both the ground and first floors on the outer left side.

The north elevation features a gabled bay at the center with a curved staircase leading to a corniced doorway on the first floor. There is a flat-roofed addition to the left, with irregular windows at the ground level and one window on both the outer right and left sides of the first floor. The interior has not been seen.

The villa has plate glass sash and case windows, a grey slate roof with ashlar coped skews, and a taller ashlar stack on the left gable. There are also two flat-roofed, slate-hung dormers with a rooflight between them on the south and north elevations.

The boundary wall is made of rubble, with square-plan piers that have rounded caps.