There was a church on the site of St Mary's since circa 1328, erected by Henry de Gower, Bishop of Saint David's. One Sunday morning, in 1739, the roof of the nave collapsed into the church while the congregation was waiting to enter the building. The whole structure was re-built apart from the tower. 1822 saw the church being lit by gas for the first time with thirty six lamps. The church underwent complete renovation between 1879 and 1882 by Vicar Dr Morgan. In 1896, the church was flattened and rebuilt again under the designs of Arthur Blomfield by Dean Allan Smith, though some parts of the old church survived the re-development. In February 1941 the church was extensively damaged by Bombing during the Blitz. It was not rebuilt until the 1950s.
From the 1890s the Swansea Devil stood on a set of buildings facing the west side of the church, constructed by a disgruntled rival of Blomfield's, angry at the commissioning of Blomfield's designs over his own.
References:The Jan Hus Memorial stands at one end of Old Town Square. The huge monument depicts victorious Hussite warriors and Protestants who were forced into exile 200 years after Hus, and a young mother who symbolises national rebirth. The monument was so large that the sculptor designed and built his own villa and studio where the work could be carried out. It was unveiled in 1915 to commemorate the 500th anniversary of Jan Hus' martyrdom. The memorial was designed by Ladislav Šaloun and paid for solely by public donations.
Born in 1369, Hus became an influential religious thinker, philosopher, and reformer in Prague. He was a key predecessor to the Protestant movement of the sixteenth century. In his works he criticized religious moral decay of the Catholic Church. Accordingly, the Czech patriot Hus believed that mass should be given in the vernacular, or local language, rather than in Latin. He was inspired by the teachings of John Wycliffe.