The Church of the Most Holy Redeemer, Porthmadog, was built in 1933 to designs by G. Rinvolucri, an Italian architect who was originally brought to Wales as a prisoner of war. He lived and worked in North Wales, and designed a number of other churches in Wales, including those at Abergele and Amlwch. This church was originally designed with a concrete roof, but the steep slate roof was added in the 1960's.

The church is in simplified Romanesque style, with Arts-and-Crafts influence. The nave, rached up a steep flight of stone steps, has boarded doors with strap hinges, under a lintel with date and the inscription 'ADDOLWYN A CHLODFORWN DI O GRIST. DHERWYDD TRWY DY CROES FENDIGAID TI A BRYNAiST Y BYD. The tympanum has thin voussoirs, and a representation of Christ on the Cross in low-relief - probably marble. It is inscribed with the text 'ADOREMUS TE ET BENEDICIMUS TIBI QUIA SANCTUM CRUCEM REDEMISTI MUNDUM'. To the right and left are small round-headed windows with steel-framed glazing and incorporating pivoting lights. Above is a large cross in low relief, superimposed on a round window.

The barn-like interior has a plaster tunnel vault, and plaster stripped to reveal rubble-stone walls. The chancel apse is blue mosaic and incorporates the figure of a dove. Apses in the side walls are in gold mosaic, and have fine stone statues of the Madonna and child and Christ the Redeemer; mosaic and statues are the work of Jonah Jones. Flanking the east apse are two round-arches: that to right is door to vestry over which is a high relief (timber?) mandorla with the Blessing of Christ; that to left contains a memorial of 1974, with a panel made up of fragments of medieval stained glass. The arrangement of the sanctuary reflects adaptation in the 1960s following the Second Vatican Council: the original rails remain, but other fittings are of the 1960s: altar and ambo are stone with marble framing, and have raised incised slate panels (also the work of Jonah Jones); the polished slate paschal candle-stand is an integral part of this design.

Reference: Cadw listed buildings description.