The water body along the western edge of Cardiff Castle is known as the Mill Leat. A ‘leat’ is a name for a man-made water body, and in this case it was created to power a mill.

The water body follows the line of a 12th century mill stream, which was originally constructed to bring water from the river Taff to power corn mills.

According to historical records, mills occupied the area to the south of Cardiff’s West Gate for several hundreds of years. They were also used for milling other commodities over the years and periodically fell into disrepair.

In the mid-19th century the Dock Feeder Canal was constructed and a dam was installed to divert the course of the water north of Cardiff Castle. This cut off the leat from its source and transformed the feature into an ornamental pond and moat along the western wall of the castle.

The leat contained water up until the late 1970s, after which it was drained following a drowning and intermittent problems with flooding of the basement of the Angel Hotel on Castle Street. The area then went into decline. The channel became overgrown and the site was a magnet for anti-social behaviour.

Restoration work was carried out in 2013 as part of the Heritage Lottery-funded Bute Park Restoration Project, and water was restored once again. Two new dams were constructed as part of the works and a liner was laid so the water is now fully self-contained. The water is circulated by a pump and kept aerated via an upper pond and gravity-fed cascade.

You can visit the site for beautiful views and reflections of Cardiff Castle. There are also a number of interpretation panels containing further information about the site’s history on West Gate Bridge.