ShotHotspot has mapped 12 abandoned places in Merthyr Tydfil, Wales, ranked by how often they're photographed, viewed and voted for. The most popular are Cefn Glas Tunnel Vonr, Pont Sarn Viaduct Merthyr and Memory Ground Chapel Burial. Some are private property or unsafe, so get permission before you visit.
We don't know whether you're allowed to visit any of these places. Many are private property, closed to the public or unsafe: get permission from the owner or the relevant authority, and take safety precautions.