3 Mill Street

3 Mill Street is part of a terrace of four estate cottages built in the third quarter of the 19th century, specifically designed for Lord Penrhyn after he acquired the estate in 1856. The cottages are constructed from rubble and feature shallow-pointed slatestone lintels over the ground floor openings. They have a continuous slate roof with a tiled ridge and deep verges.

There are two chimneys, shared between nos 1 and 2 and nos 3 and 4, each with a two-stage design that includes a rendered lower section and a stone upper section, adorned with plain cornice bands. The cottages are arranged as one-window reflected pairs, with nos 1 and 4 having outer entrances, while nos 2 and 3, the central units, have inner entrances.

The doors are half-glazed and date from the 20th century, while the ground floor features 6-pane sash windows with projecting cills. The upper windows are also 6-pane sashes, set within mid-20th century flat leaded dormers that break the eaves. At the rear, each unit has a modern door and window combination, along with paired modern dormer windows on the upper floor.