Holy Trinity was established as a German parish in 1857. The parish was the result of the growth of the German population in the Hill District, then known as Riceville. Part of the growth stemmed from new immigrants coming to Pittsburgh. Another part was the result of the build up of industry and business along the Allegheny River, which displaced the residents living there. Among the displaced residents were parishioners of St. Philomena parish. Seeing the need for a church and school for the growing community, the Redemptorist Fathers from St. Philomena held a meeting to plan the erection of a separate parish on September 21, 1856. This meeting led to the purchase of land for a church and school and a subsequent meeting, held on October 12, 1856, led to a decision to build a brick church. As work was not to begin on the church until May of 1857, a temporary chapel was soon erected. This chapel was a mission of St. Philomena.
The cornerstone for the new church was laid on June 7, 1857, and the completed church was dedicated on November 22, 1857. In that same year a resident pastor was assigned to the parish. The parish grew rapidly, requiring the church to be enlarged twice. Even with these additions, by the end of the century the parish decided to build a new church. Land across Crawford St. from the original church was purchased in 1892 and construction of the new church began on August 1, 1893. The cornerstone of the new church was laid on May 20, 1894, and the completed church was dedicated on August 4, 1895. The old church was then converted into an auditorium.
Unfortunately, the quality of the sandstone used in the turrets and around the windows of the new church was poor and soon began to deteriorate. In 1929 extensive repairs were made to the stone work of the church, including replacing several turrets that had fallen down. In 1930, the church was refrescoed.
Of a more serious concern to the parish, however, was the changing population in the Hill District. As early as the first decade of the twentieth century, the German residents of the Hill District began moving to Oakland and East Liberty for economic reasons. As the century progressed, the movement of parishioners out of the area accelerated. By 1958, the Catholic population had dropped to the point that the area could no longer support the number of parishes in existence. On April 16, 1958, Holy Trinity was merged with St. Brigid parish. The new parish retained the name St. Brigid, but the original St. Brigid Church was torn down and Holy Trinity Church then became St. Brigid Church.
The year 1958 also saw the loss of the original Holy Trinity Church. That building, which had been converted to a parish auditorium once the new church was built, was sold and torn down to make room for a parking lot for the new Civic Arena.
The new St. Brigid parish only had a short life span. On May 14, 1968, the parish merged with St. Benedict the Moor to form the new St. Brigid-St. Benedict the Moor parish. As with the earlier merger, the original St. Benedict the Moor Church was torn down and the former Holy Trinity Church became the parish church and was again renamed. On July 1, 1977, this parish was in turn merged with St. Richard and the new parish was renamed St. Benedict the Moor. As with the other mergers, St. Richard Church was closed and the original Holy Trinity Church became St. Benedict the Moor Church. This church remains and continues to serve St. Benedict the Moor parish.
