In the United Kingdom, the term listed building refers to a building or other structure officially designated as being of special architectural, historical, or cultural significance; Grade I structures are those considered to be "buildings of exceptional interest". Listing was begun by a provision in the Town and Country Planning Act 1947. Once listed, strict limitations are imposed on the modifications allowed to a building's structure or fittings. In Wales, the authority for listing under the Planning Act 1990 rests with Cadw.

Ewloe Castle is a native Welsh castle built by the Kingdom of Gwynedd near the town of Ewloe in Flintshire, Wales. The castle, which was one of the last fortifications to be built by the native Princes of Wales, was abandoned at the beginning of the invasion of Wales by Edward I in 1277. Its construction, using locally quarried sandstone, appears to have continued piecemeal over many years and may have not been completed. On taking the castle, the English Crown gave it little military value and allowed it to fall into ruin.