Merthyr Tydfil on Wikipedia.
 

Abercanaid, St. Peter & St. Paul (CiW, 1882). Another view. © Gerard Charmley (2011). The original became too small, and another church was built adjacent (1912). Gerard advises that it appears to be disused. Both © Gerard Charmley. Sion Welsh Independent Church. © Gerard Charmley.
Aberfan.

Bedlinog.

Cefn-Coed-y-Cymmer.

Dowlais.

Edwardsville, U.R.C., originally English Congregational (1900). Merthyr Tydfil, © Gerard Charmley (2011).

Heolgerrig, Calfaria Baptist Church (1902). All that remains of Salem Welsh Independent Chapel is the vestry. The rest of the chapel was demolished in 1990. Cephas Presbyterian Church. All © Gerard Charmley (2011).

Llwyn-On, Bethel Baptist Chapel. Originally founded in 1799 in Twynyrodyn, it was removed and re-erected at Llwyn-On in 1914. © Eirian Evans.

Merthyr Tydfil.
Merthyr Vale, St. Mary (CiW). © Gerard Charmley (2011). St. Benedict (R.C.). © Gerard Charmley (2011). Baptist Church. The derelict Calvinistic Methodist Chapel. Both © Gerard Charmley. A much happier photo of the CM chapel, undergoing conversion in 2011. © Gerard Charmley (2011). All that remains of Trinity Presbyterian Chapel is the former vestry. The chapel itself was demolished in the 1970's. Additional information from Steve Brewer. © Gerard Charmley (2011).

Pant, Dowlais - see Dowlais.
Penydarren, St. John (CiW, closed). Horeb Independent Chapel. Both © Gerard Charmley.
Pentrebach, Jerusalem Baptist Church. © Gerard Charmley (2011).
Pontsticill, the former Sion Chapel, now in secular use. Bethlehem Chapel, also now in secular use. (Corrections advised by Steve Brewer). Both © Gerard Charmley.

Quaker's Yard, the former Berthlwyd Baptist Chapel on Pentwyn Road, now in residential use. ST 1002 9619. © Gerard Charmley (2011).

Treharris.
Trelewis, the former St. Mary (CiW). Trinity Baptist Church. Kingdom Hall of Jehovah's Witnesses. All © Gerard Charmley (2011).
Troedyrhiw.
Twynyrodyn - see Llywyn-On above.

Vaynor, St. Gwynno. Compare with photos on this link - whatever happened to the spire? © Gerard Charmley.