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 (Listed Buildings and Conservation Areas) Act 1990 rests with Cadw.
|Name||Location||Date Listed||Grid Ref.[note 1]
|Function||Notes||HB No[note 2]||Image|
|Cyfarthfa Castle||Park||15 July 1974||Country House||11396|
|School at Cyfarthfa Castle||Park||15 July 1974||School||11397|
Media related to Grade I listed buildings in Merthyr Tydfil at Wikimedia Commons