A high breastshot design, it was retired in 1904 and replaced with several turbines. It has now been restored and is a museum open to the public. The biggest working waterwheel in mainland Britain has a diameter of 15.4 m and was built by the De Winton company of Caernarfon. It is located within the Dinorwic workshops of the National Slate Museum in Llanberis, North Wales. Modern Hydro-electric dams can be viewed as descendants from water wheel history - as they too take advantage of the movement of water downhill.