Moriah Chapel was fostered by Zion, the oldest of the town’s Baptist churches, to accommodate an overflow of members. In April 1870, on a Tuesday evening at 5 o’clock, a large crowd gathered on the site of the new chapel on the corner of the Old Castle Road, opposite Bradbury Hall. The reason for the interest was the laying of the foundation stone by the Revd J R Morgan (Lleurwg), minister of Zion Chapel. He chose to read part of the scripture being the 7th chapter of the 2nd Samuel, which contained the narrative of Nathan the prophet approving the purpose of St David, and authorising him to build a House for the Lord to dwell in.

Mr John Powell, mason, laid the stone and the Revd Dr Price of Aberdare delivered an interesting address on the subject of the chapter read by Revd Morgan. The Revd W Hughes of Bethel, Seaside, then offered a prayer, a hymn was sung and the gathered crowd went their separate ways. The local newspaper commented on the indefatigable perseverance and the great exertions made by the Baptist movement in Llanelli and the fact that no fewer than eight new places of worship had been established.

The Baptists had also embarked on a programme of rebuilding and enlarging the old places of worship. Moriah was intended to be the largest in Llanelli and the contractors were Messrs John Powell and J David.

In September 1870 John Powell, and David Jenkins, both masons, were involved in an accident during building operations. Powell, who was the main contractor for the masonry work on the chapel, was supervising the lifting and placing of the large coping stones, which weighed several hundredweights each. Several of the copings which extended over the front half of the building, gave way and fell onto the scaffolding. The scaffolding was not strong enough to bear the weight of the copings and gave way, hitting the ground with a tremendous crash. Both Powell and Jenkins had been on the scaffolding when it collapsed. John Powell was killed almost instantaneously and David Jenkins was seriously injured.

John Powell had been involved with almost every important building in the Llanelli, employing a large number of workmen, and when he died he left a widow and seven children.

Moriah opened its doors to the public in 1872.