Situated 1km south west of Ruabon at the former Wynnstay Colliery is this vertical winding engine house, built 1855-6 as one of the original structures of the Wynnstay Colliery.

Of sandstone ashlar with cast iron fixings, the south east elevation has tall arched openings with a stone architrave and keystone which reaches almost to eaves level. On each side is a similar lower arched opening. The interior is divided into three chambers by massive masonry walls. The side chambers have massive stone engine beds. Listed Grade II* as an exceptionally good example of the building type which is said to be the oldest surviving architectural monument in the North Wales Coalfield. It is also a Scheduled Ancient Monument. On the otherside of the main road is a listed fan house which is structurally complete and includes the fan drift annexe. There are further workshops, engine shed and also the managers house. The site is located at SJ293432.