The plans and drawings were donated free of cost to the church by John Rudolph Niernsee, who also designed the State House in Columbia, SC. The church is a classic example of the Early Romanesque Revival style of church architecture, with smooth, broad exterior wall surfaces. The cornerstone was laid July 19, 1857 and the building was consecrated April 12, 1863. The front part of the building is divided into three sections marked by piers. The left section is a tower of three levels or stories. The right section is a bell tower of three levels with a belfry and spire above the third level.
The building is plaster over hand-made brick. The semicircular arch form, the definitive unit of the Romanesque style, is found in the main double doorway framed in granite arches, in the central windows of the front facade, in the narrow niche-windows of the east and west bays and also in each facade of the octagonal base of the spire.
The front facade is lighted not only by the central tracery stained glass, but also by three other small rose windows, one in each bay. Recessed cruciforms between the bays complete the detailing of the front facade. The major features of the side facades are the six large stained glass windows separated by slightly projecting buttresses. Typically, the chancel is lighted by semicircular arched stained glass windows in the rear wall.
Smith & Crane Carvers of New York served as the building's contractor. The brick for the church was furnished by Nicholas del'Aigle and Ferdinand Phinizy and the brick work was executed by Messrs. Hitchcock and Ingalls of Augusta, Georgia. The base of the tower on the southeast corner contains 180,000 bricks. The gable Buttresses and sidewalls, average 8 1/2 feet wide and 10 feet below the surface and contain 630,000 brick. In 1886, the church was "rocked by a great earthquake but the church clung to its massive foundations and stood without crack or flaw." The rough casting and plastering by Messrs. James and T. Devereaux of Charleston, South Carolina; the carpenter work was superintended by Isaac Hess and Mr. Dunn until the roof was put on; the interior carpenter work, pews, screen, railing, etc., were executed by Mr. James Osmond.
The iron columns of the interior and the cross on the front of the church were manufactured at the foundry of Mr. John MacMurphy, and are an enduring monument of Southern skill and workmanship.
The fresco painting in the Sanctuary ceiling was originally the work of Messrs. Lamkau and Kreuger. (In 1963 the painting was completely redone by Adolph Frei & Sons, Inc., ecclesiastical artists from Philadelphia.)
The marble altars were done in Baltimore, Maryland by John P. Mullen. He smuggled the altars through the union blockade at the height of the Civil War to install them for the consecration. A bell donated by the Dorr family in 1894 prompted the completion of the bell tower and spire. Granite steps, replacing wooden originals, and an brick and iron fence added to the church in 1899 finished the exterior that we see today.
Rev. Gregory Duggan 1854-1865 Assistant to Fr. Barry 1841-1854; pastor when the new church was built; interred under the church
· Rev. Peter Whelan Assistant 1854
· Rev. James Hasson Assistant 1856
· Rev. John F. Kirby 1865- 1870 Assistant 1854-1865; interred under the church
· Rev. B. OHara Assistant 1867
· Rev. Louis Denis Xavier Bazin Assistant 1867-1870; Jardine organ installed 1868
· Rev. Abram Ryan Assistant 1868; poet priest of the confederacy; Jardine organ purchased with proceeds from poetry readings and lectures
· Rev. James O'Hara Assistant 1871-1873; buried under the church
The pipe organ in the Church of the Most Holy Trinity is thought to have been built in New York during the Civil War but not installed until October 1868 because of the Union blockade of Southern ports. Built by George Jardine and Son of New York City, it contains 1,520 pipes. The organ was the first large instrument built by Jardine for a Southern church in the Post-bellum period. In 1994, the organ was completely restored by Messrs. Henry Hawkinson and Morris Spearman of Charlotte, North Carolina and was selected by the Organ Historical Society as "an instrument of exceptional historic merit, worthy of preservation." Most Holy Trinity's organ is the largest extant 19th-century organ remaining in the South and one of the largest Jardines in the country.