The original St John's catholic church, Rhymney was built c1861. A contempoary newspaper report of its opening in 1861 has the following description of the building: 'twenty-four feet in height, fifty-six in length, and thirty-two wide, and constructed to contain about 400 persons with seats, beside other accommodation. On the one side is the clergyman's residence, to which the Rev. Mr. Dawson has removed from Tredegar. On the other are spacious schools, The architect is J. Trump, Esq., and the contractor Mr. Taylor, Tredegar'. Reference: The Cardiff Times, 9th August 1861, accessed from Welsh Newspapers Online. This church was demolished in the 1960s due to subsidence caused by mining activies. 

The present church was built in 1965 to designs by F. R. Bates, Son & Price on land adjacent to the old church site. It was built on a concrete raft to counter the threat of subsidence. The presbytery was built on the site of the old church, also on a concrete raft. The church is a low-lying concrete framed building with walls of rendered blockwork and sections faced with buff brick. The roof is a low pyramid with tile coverings. The lower windows have slate sills, and the entrance is at the corner.

Inside, two walls of the sanctuary and main worship area have been covered with full-height oak veneered panelling. The font is located close to the entrance; it is conical and constructed of black terrazzo with a hardwood lid and an applied mosaic of the Holy Dove descending. Beside it is a small stained glass panel of the Sacred Heart, formerly in the old church. The altar is up a further step, and is constructed of granite with a single large block and overhanging mensa.

The church was the first in the archdiocese to be designed on a radiating seating plan, with the benches converging around a sanctuary placed in the corner. 

Reference: The Taking Stock Project, 2018.